THE MOUNTAIN ANTS OF WESTERN NORTH AMERICA.^ By William Morton Wheeler. Received September 12, 1916. The study of several collections of ants received from Professors J. C. Bradley, C. F. Baker, T. D. A. Cockerell, C. C. Adams, S. J. Hunter, Dr. W. M. Mann, Dr. R. V. Chamberlin, Mr. E. J. Oslar and others and of my own collections made during several seasons in Colorado, New Mexico, Texas, Arizona and Southern California, and especially during the summer of 1915 in the Yosemite Valley and at Lake Tahoe, California and in the Canadian Rockies, enables me to give a much more consistent and comprehensive account of the dis- tribution of the Formicidae of Western North America than was possible heretofore. These collections represent two distinct faunas, one of which belongs to Merriam's Lower and Upper Sonoran Zones and comprises species of several neotropical and tropicopolitan genera and subgenera, while the other, occurring at higher elevations belongs to Merriam's Transition and Canadian Zones and is repre- sented by species of the genera Monomorium, Solenopsis, Myrmecina, Myrmica, Leptothorax, Aphaenogaster, Stenamma, Liometopum, Tapi- noma, Prenolepis s. str., Lasius, Formica, Polyergus and a few sub- genera of Camponohis {Camponotus s. str. and Myrmoturba). There is some overlapping of the Sonoran and mountain faunas due to the ascent of such forms as Pogonomyrmex occidentalis, Myrmecocystus- mexicamis and a few species of Crematogaster, Pheidole and Solenopsis- into the Transition Zone and the descent of a few species of Campo- notus s. str., Myrmica and Formica into the Sonoran Zones. In the following pages I have listed the known forms belonging to the Transi- tion and Canadian Zones of Western North America and have added descriptions of 32 new forms (three species, twelve subspecies and seventeen varieties) which I have been able to recognize among the recently collected material. I have not included any of our Pone- 1 Contributions from the Entomological Laboratory of the Bussey Institu- tion, Harvard University, No. 118. 458 WHEELER. rinae in the list, because the distribution of the species of Ponera, Stigmatomma, Proccratium and Sysphincta, with the exception of Ponera coardata subsp. pcnnsylvanica, is imperfectly known, and because I have no new data for publication. The ants of the genera Proceratium and Sysphincta are very rare and seem to belong to the Upper and Lower Austral Zones, but they will probably be dis- covered in the Western States. I have, in fact, seen a male specimen which seems to belong to one of these genera, from California. Ponera pennsylvanica is confined to the Eastern and Central States, Ontario and Nova Scotia. The genus is represented in the Western and Southern States by at least two closely allied species (P. trigona var. opacior and P. opaciceps), whose precise distribution is still unknown. The great importance of the ants in the study of geographical dis- tribution has not been overlooked by students of this fascinating sub- ject. These insects are, indeed, specially fitted for the mapping of geographical areas, for several reasons. They are not, like many other groups of insects, absolutely dependent on specific food-plants, their colonies are stable and stationary entities, chained to the soil or to certain general plant associations, and they are exceedingly sensitive to climatic and other environmental influences as shown by the extraordinary development of geographical races (subspecies) and varieties in practically all the species of extensive range. A few authors have attempted to minimize these peculiarities on the ground that the marriage-flight of male and female ants must permit of a wide dissemination of the species. It is true that many species of ants have a very wide range, e. g. Formica fusca, which is circumpolar and Camponotus maculatus which is cosmopolitan, but this is, in all proba- bility, the result of great geologic age, and while we must admit that the nuptial flight of the female ant is practically the only means of rapidly disseminating the species, it is easy to exaggerate its impor- tance. It is natural to suppose that small flying insects, like many female ants, must be carried long distances by air-currents, and these females, when fecundated, are, of course, so many potential colonies. But such observations as can be made in the field do not support this supposition. Most female ants are heavy-bodied and have feeble powers of flight. Moreover, the time during which they can use their wings, especially after fecundation, is limited to a few hours at most. The wing muscles very soon begin to degenerate and compel the insects to descend, abandon their organs of flight and become as completely terrestrial as the workers. During marriage flights female MOUNTAIN ANTS OF NORTH AMERICA. 459 ants are therefore usually observed to return in great numbers to the ground at no great distance from their parental nests. The height to which ants are able to ascend on their nuptial flights will be ascertained only when some of our young myrmecologists become aviators. We know that winged ants are often carried to high mountain peaks. Forel (1874) records the occurrence of males and females of Formica nifa and pratensis on the perpetual snows of Alpine glaciers, and Mrs. Slosson sent me several male and female ants of different genera from the summit of Mt. Washington, N. H. (Wheeler 1905). I have myself taken similar specimens on the summits of other peaks in the White Mountains. But, as Forel has shown, female ants never succeed in establishing colonies at these altitudes. They are merely transported to the summits by the air-currents which are known to ascend mountain slopes during the day-time and to carry up great numbers of insects of all orders. Unless, therefore, such females were able to descend on the opposite slopes, — and this is probably of very rare occurrence — high mountain ranges must constitute barriers as effective as are considerable bodies of water or deserts to the dis- tribution of most ants. I am convinced that the Sierra Nevada in California is such a barrier to many forms common on the Pacific Coast and in Europe the Alps certainly act as a similar barrier to many species common in Italy and Central Europe. For the purpose of bringing before the reader as clearly as possible the results of my study of the ants of the Transition and Canadian Zones, I have cited the various species, subspecies and varieties from the Coast Range of California, the Sierra-Cascade Ranges, the Rocky Mountains and the portion of North America east of these ranges in four columns in the accompanying Tables I to IX (pp. 464 to 481). As might be expected, the great ranges of the Rocky Mountains, from British America to Mexico, show the greatest number and diversity of forms. The Eastern portion of North America has, with the exception of a certain number of holarctic and neotropical species, a fauna peculiar to itself, and the Sierras and Californian Coast each possesses peculiar elements, though also possessing many forms in com- mon with the Rocky Mountains. One is struck in the tables by the meagerness of the two Californian moiintain faunas. This might be attributed to their much smaller territory, but such can hardly be a complete explanation, for ant-colonies in California, even those of the more dominant species, are much less numerous than they are in the Rocky Mountains and Eastern States. I believe that the difference is due to the peculiar annual distribution of temperature and mois- 460 A\TIEELER. ture in California. The ants of the Transition and Boreal Zones re- quire a considerable amount of humidity and warmth during their breeding season. These conditions are not realized simultaneously in California, where the rainy season comes during the winter and the summer is rainless except in the high Sierras. The more perfect adaptation of the species of the Sonoran zones to a smaller amount of moisture and to winter temperatures not sufficiently low to inhibit completely the activities of the worker ants, probably accounts for the greater number of species and colonies at lower altitudes in Southern California, where the conditions are much like those of Arizona. Even moderately low temperatures, when coupled with considerable humidity, a condition which prevails in California dur- ing the winter months, is very unfavorable to ants, and when such conditions are most accentuated, the ant-fauna is reduced to a mere remnant, although the vegetation, if the temperature is not too low, may be luxuriant. This is the case in New Zealand where I some- times searched in vain for an ant-colony in forests whose luxuriance rivalled those of the tropics. But we have a striking example of the depressing effects of cold and moisture on ant-life much nearer home. The cool Selkirk Mts. of British Columbia have an abundant supply of moisture and an unusually rich flora, but their ant-fauna is reduced to a few boreal species. The adjacent Canadian Rockies, however, though in the same latitude, are less humid and have a poorer flora, but their ant-fauna is decidedly richer in species and colonies. In mountain regions slope exposure in its relation to insolation is a very important factor in the local distribution of ants, but it is impossible at present to give more than a general statement in regard to this matter. Northern slopes in the northern hemisphere are usu- ally, for very obvious reasons, almost or quite destitute of ants. In regard to the other slopes ray observations in the Alps of Switzerland and the mountains of the United States, British America, Mexico and Central America confirm those of Forel in the Alps and the mountains of North Carolina. He finds that ants prefer the eastern and southern slopes as these are the situations in which they have the longest day for their activities during the breeding season, since they are early awakened by a sufficiently high temperature of the soil and air from the lethargy induced by the chill night hours, and even though the slope may be in shade during the afternoon the warmth is sufficient to sustain their activities till sun-set. On western slopes, however, the morning hours are too cool and are therefore practically lost to the ants, whereas the afternoon hours are too warm. MOUNTAIN ANTS OF NORTH AMERICA. 401 This preference of our northern ants for eastern and southern slopes is further confirmed by the shape of the nest and the position of the nest-entrance of certain species. This matter was considered in my ant-book (1910, p. 205) in the following passage: "I have already called attention to the constant position of the nest opening at the base of the southern or eastern slope of the mounds of Pogonomyrmex occidentalis. Huber says that the yellow ants {Lasius flavus) of Switzerland "serve as compasses to the mountaineers when they are enveloped in dense fogs or have lost their way at night; for the reason that the nests, which in the mountains are much more numerous and higher than elsewhere, take on an elongated, almost regular form. Their direction is constantly from east to west. Their summits and more precipitous slopes are turned towards the winter sunrise, their longer slopes in the opposite direction." These remarks of Huber have been recently confirmed by Tissot (Wasmann 1907) and Linder (1908). The latter has shown that the elongate shape of the mounds is due to the fact that the ants keep extending them in an easterly direction in such a manner that only the extreme easterly, highest and most precipitous portions are inhabited by the insects. I have observed a similar and equally striking orientation of the mounds of Formica argentata [fusca var. argtmtea] in the subalpine meadows of Colorado." In the southern hemisphere, as we should expect, the ants prefer the northern and eastern slopes of the mountains. I found many striking instances of this preference while collecting in the moun- tains of New Zealand, New South Wales and Queensland. Merriam and his collaborators in their studies of the floras and faunas of the mountains of western North America have published interesting observations which deserve consideration since they have a bearing on the distribution of the Formicidae though they show that these insects would hardly suffice to determine the boundaries of the various life-zones on mountain slopes. In his work on Mt. Shasta, Merrian (1899) says: "The influence of slope exposure on the faunas and floras of mountain regions is profound. Measured by a scale of altitudes it amounts on ordinary slopes to nearly a thousand feet and on steep slopes is still more marked. Thus on mountains it is usual for plants and animals of particular species to occur on warm south- westerly slopes at elevations 800 to 1000 feet higher than on cool northeasterly slopes — similarly on north and south ridges, the fauna and floras of the warm west slopes often belong to lower zones than those of equal elevations on the cool east slopes." Merriam had pre- viously shown the existence of very similar conditions in a very differ- 462 WHEELER. ent region, the San Francisco Mountains of Arizona (1890). There he found the normal difference in altitude of the same zone on the south- west and northeast slopes to be about 900 feet. After giving numerous examples of this altitudinal distribution on Mt. Shasta, he calls attention to other factors, besides those of insolation, which influence the range of plants and animals: "It is well-known that in ordinary calm weather the air-currents on mountain sides and in deep canyons ascend by day and descend by night. The ascending currents are warm, the descending currents cold. The night current, being in the main free from local influences that affect its temperature, must exert an essentially equal affect on all sides of a mountain ; but the tempera- ture of the ascending day current, being constantly exposed to and in fact created by the influence of the sun, must vary enormously on different slopes. The activity and effectiveness of this current increase with the steepness of the slope and the directness of its exposure to the afternoon sun. Hence the hottest normal slopes — those that face the sun at nearly a right angle during the hottest part of the day — are rendered still more potent by increased steepness, the direct exposure of the sun keeping up the supply of heat while the steepness of the slope accelerates the rate of movement of the diurnal ascending current, carrying the heated air upward a very great distance before it has time to be cooled to the general temperature of the stratum it penetrates. Thus it is that species characteristic of the Transition zone on Shasta — species which on normal south- westernly slopes attain their upper limits at an altitude of 5500 to 5700 feet — are in favorable places enabled to live at elevations of 7900 or even 8000 feet, considerably more than 2000 feet above their normal limits." Every observer in the field must have been impressed with the fact that steepness of slope is an important factor in the local distribution of mountain ants. These insects always greatly prefer the more gradual slopes and alpine meadows, probably because the soil of such places retains a more abundant and more equable supply of moisture and because their surfaces are much less exposed to rapid evaporation both from direct insolation and from air-currents. All of these eco- logical factors demand much more careful study. It is, of course, well known that the delimitation of the various life-zones in mountain regions depends not only on slope-exposure but also on latitude. That the upper limit of the zones descends in more northern and ascends in more southern latitudes even within the confines of a single one of our western states is well shown in the fol- MOUNTAIN ANTS OF NORTH AMERICA. 463 lowing table from Gary's "Biological Survey of Colorado" (1911); In his "Life Zones and Crop Zones of New Mexico, Bailey (1913) gives the upper boundary of the Upper Sonoran as 5000-7000 or even 8000 ft., the boundaries of the Transition as extending from 7000 to 8500 ft. on northeastern and 8000 to 9500 on southwestern slopes, of the Canadian as from 8500 to 11,000 and on warm slopes from 9500 to 12,000, of the Hudsonian from 11,000 to 12,000 on northeastern and 12,000 to 13,000 on southwestern slopes, the Arctic-Alpine on the Sangre de Cristo Range as all above 12,000 ft. on the coldest slopes, and on especially steep slopes as all above 11,500 ft.; on the warmest slopes as all above 13,000 ft. or on very gradual slopes all above 12,500 ft. In Arizona the boundaries of the life-zones ascend some- what higher, as indicated by the following altitudes from Merriam's work (1890) on the San Francisco Mountains (southwest slopes): Lower Sonoran 4000-6000 ft.. Upper Sonoran 6000-7000 ft.. Transi- tion 7000-8200 ft., Canadian 8200-9200 ft., Hudsonian 9200-10,500 ft., Arctic-x\lpine 10,500-11,500 ft. In the Chisos, Davis and Guadeloupe Mountains of Western Texas, according to Bailey (1905) the Transi- tion Zone extends from about 6000 ft. on northeast slopes to the top of the ranges (8000-9500 ft.). In Mexico the upper boundary of the Transition must be even higher. North of Colorado the zonal bound- aries descend rapidly till in the latitude of Vancouver and Maine the Canadian zone, which extends across the continent, is at sea-level, so that we find at this level such forms as Camponotus whympcri, modoc, and larvigatus, the two latter of which do not descend below 4000 to 6000 ft. in the Sierras, while whyrnperi and laevigatiis are not known from elevations under 7000 to 8000 ft. in Colorado. On the other 464 WHEELER. \ Table I MOUNTAIN ANTS OF NORTH AMERICA. 465 466 WHEELER. Table Symmyrmica Harpagoxenus Symmyrmica Harpagoxenus MOUNTAIN ANTS OF NORTH AMERICA. 467 II. 468 WHEELER. Table MOUNTAIN ANTS OF NORTH AMERICA. 469 III. apiculatum subsp. luctuosum 470 WHEELER. Table I I i MOUNTAIN ANTS OF NORTH AMERICA. 471 IV. 472 WHEELER. Table MOUNTAIN ANTS OF NORTH AMERICA. 473 V. 474 WHEELER, Table I MOUNTAIN ANTS OF NORTH AMERICA. 475 VI. 476 WHEELER. Table MOUNTAIN ANTS OF NORTH AMERICA. 477 VII. 478 WHEELER. Table MOUNTAIN ANTS OF NORTH AMERICA. 479 VIII. 480 WHEELER. Table MOUNTAIN ANTS OF NORTH AMERICA. 481 IX. c. Rocky Mountain Transition and Boreal Camponotus maculatus subsp. vicinus var. plorabilis var. luteangulus var. nitidiventris var. infernalis subsp. sansaheanus var. torrefadus subsp. bulimosus fumidus var. festinatus var. spurcus vafer acutirostris var. clarigaster ocreatus subsp. primipilaris mina subsp. zuni bruesi uleerosus pylartes var. hunteri abditus var. etiolatus D. Eastern Transition and Boreal Camponotus impressus 482 WHEELER. hand, in the Huachuca Mountains of Arizona such neotropical forms as species of Eciton, Odontomachus, Pheidole, etc. are abundant at alti- tudes of 4000 to 6000 ft.2 Before considering the historical problems suggested by the ant- faunas of the four regions of the tables, it will be advisable to analyze them more closely. The total number of forms recorded for all the regions is 422 distributed as follows : A B C D 58 or 13.7% 60 or 14.2% 180 or 42.6% 124 or 29.4% In reality the total number of different forms is only 311. If we count only the forms peculiar, endemic, or precinctive to each region (printed in italics in the tables) we have the following: 29 18 112 75 234 There are therefore 77 forms common to two or more of the regions. This would yield the following percentages for the given groups: The total number of endemic forms in the western fauna (A + B + C) is 159 or 68%, whereas the 75 eastern forms represent only 32%. The number of forms in common gives a good index of the affinities of the different regions, and may be tabulated as follows: 2 In his interesting paper on the insects of Custer County, Colorado, Cockerel! (1893) does not accept Merriam's terminology for the life-zones of that region. He distmguishes three zones, a "subalpine," up to about 6500 ft., a "mid- alpine" between 6500 and 10,000 ft. and a "high-alpine" zone above the latter elevation, and correlates these with Merriam's zones in the statement that "an analysis of the insects of the Colorado Mountains shows that the high-alpine and mid-alpine elements, though sufficiently distinct, are both essentially boreal. If we follow Dr. Merriam's arrangement, it appears that the high-alpine is truly boreal, while the mid-alpine belongs to the transition region, containing a considerable number of strictly American types. The subalpine, on the other hand is southern or Sonoran." MOUNTAIN ANTS OF NORTH AMERICA. 483 As would be expected, the affinities between the Pacific Coast knd Eastern faunas are least developed, while those between the Sierra- Cascade and Rocky Mts. and especially those between the latter and the Eastern fauna are much greater. If to the Transition and Boreal forms included in the tables we add the species, subspecies and varieties of the Lower and Upper Sonoran and Lower and Upper Austral Zones, the quantitative and qualitative differences between the western and eastern ant-faunas are even more striking. The same would be true of a comparison of the subgenera and genera of the two regions, for we find that, if we exclude the neotropical elements, no less than eight genera and subgenera are restricted to the western fauna {Liometopum, Mcssor, Deromyrma, 484 WTIEELER. Neomyrma, Symmyrmica and Myrmecocystus) and seven are peculiarly eastern {Bothriomyrmcx, Hypoclinea, Sirumigenys, Epoecus, Dicho- ihorax, Harpagoxenus and Brachymyrmex). Moreover certain genera are almost exclusively western or eastern. Pogonomyrmex e. g., represented by numerous species in the Southwestern States has only one species (P. badius) in the Southeastern States, and Proceratiuvi and Sysphinda are at any rate very largely confined to the East. The great majority of the forms recorded in the tables are undoubt- edly peculiar to the Transition Zone. Only the following would seem to belong to the Canadian, or boreal fauna: Myrmica brevinodis vars. sulcinodoides, canadensis, and frigida, M. scabrinodis subsp. lobicornu var. glacialis, Leptothorax acervorum subsp. canadensis and its vars. and the subsp. crassipilis, L. muscorum and its vars., L. provancheri, L. emersoni and its subspecies, Stenamma nearcticum, S. brevicorne, its subspecies and varieties, Lasius niger var. sitkaensis, L. fiavus subsp. claripemiis, L. umbratus subsp. subumbratus , Formica bradleyi, F. sanguinea and subsp. subnuda and aserva, F. rufa obscuripes and its var. melanotica, F. truncicola and its subspecies and varieties, F. whymperi and its varieties, F. dakotensis and its varieties, F. ulkei, F. fusca and its varieties neorufibarbis, marcida, subaenescens , argentea, gelida and algida and the subsp. pruinosa, F. hewitti, F. cinerea var. altipetens and canadensis, F. neogagates, its subspecies and var. vetula, Camponotus laevigatus, C. herculeanus var. whymperi and subsp. ligniperda var. novebora- censis. Most of these are what the Germans would call " stenotherm kalte- liebend" (stenothermal psychrophilous). Some of them, however, and especially those common to the foiir regions of the tables, are MOUNTAIN ANTS OF NORTH AMERICA. 485 strikingly eurythermal ("eurythermal ubiquists" of Zschokke, 1907, 1908). A list of the latter would include the following: Myrmica scahrinodis and most of its subspecies and varieties, Aphaenogaster suhterranea subsp. occidentalis , Tapinonia sessile, Prcnoh'pis imparis, Lasius nigcr subsp. alienus var. americanus, L. brevicornis, L. flavus subsp. nearcticus, Formica sanguinea subsp. ruhicunda, subintegra and subnuda, F. fiisca and its varieties subsericea and argentea, F. cinerea var. neocinerea, F. neogagates subsp. lasioides var. vetula, Polyergus rufescens subsp. breviceps, Camponotus herculeanus subsp. pennsyhanicus , C. fallax var. nearcticus, C. maculatiis subsp. vicinus and its varieties. It will be noticed that the bulk of the forms common to all four regions of the tables is made up of some eight of the forms included in this list. The ants of both the preceding lists, owing to their pro- nounced eurythermy or psychrophilous stenothermy, constitute the great majority of the forms common at higher elevations in the moun- tains of North America. Incidentally attention may be called to the high degree of melanism of nearly all the forms enumerated in these lists. This is a well-known peculiarity of many arctic-alpine insects (Cf. Zschokke, 1908, p. 42). The ant-fauna of the Nearctic Transition and Boreal Zones as a whole shows very close affinities to the fauna of the corresponding zones of the Palearctic Region, as will be evident from a study of the following list in which the most closely allied forms of the two regions are arranged in parallel columns:— Palearctic Nearctic Ponera coarctata P. coarctata subsp. pennsylvanica Monomorium minutum M. minimum Solenopsis fugax S. molesta Myrmica sulcinodis M. brevinodis M. scabrinodis var. sabuleti M. scabrinodis var. sabuleti M. scabrinodis subsp. lobicornis M. scabrinodis subsp. lobicomis var. glacialis 486 WHEELER. Palearctic M. scabrinodis subsp. schencki M. levinodis M. rubida Leptothorax acervorum L. muscorum L. flavicornis Harpagoxenus sublevis Formicoxenus nitidulus Stenamma westwoodi Aphaenogaster subterranea Tapinoma erraticum Bothriomyrmex meridionalis Liometopum microcephalum Hypoclinea 4-punctata Prenolepis imparls subsp. nitens Lasius niger L. niger subsp. alienus L. flavus L. umbratus subsp. mixtus Formica sanguinea F. rufa subsp. pratensis F. truncicola F. exsecta F. fusca F. cinerea F. rufibarbis Polyergus rufescens Camponotus herculeanus var. whymperi C. herculeanus subsp. ligniperda C. herculeanus subsp. pennsyl- vanicus C. fallax C. maculatus subsp. aetliiops C. truncatus Nearctic M. scabrinodis subsp. schencki var. emeryana. M. levinodis subsp. neolevinodis M. mutica L. acervorum subsp. canadensis L. muscorum var. sordidus L. curvispinosus and rugatulus Harpagoxenus americanus Symmyrmica chamberlini Stenamma nearcticum A. subterranea subsp. occidentalis T. sessile B. dimmocki L. occidentale H. plagiata P. imparis L. niger var. sitkaensis and neoniger L. niger subsp. alienus var. ameri- canus L. flavus subsp. nearcticus L. umbratus subsp. mixtus var. aphidicola F. sanguinea subsp. rubicunda F. rufa subsp. obscuripes F. truncicola subsp. integroides F. exsectoides F. fusca F. cinerea var. neocinerea F. rufibarbis var. occidua P. rufescens subsp. breviceps C. herculeanus var. whymperi C. herculeanus subsp. ligniperda var. noveboracensis C. herculeanus subsp. pennsylvani- cus C. fallax var. nearcticus C. maculatus subsp. vicinus C. impressus MOUNTAIN ANTS OF NORTH AMERICA. 487 In this list of 41 Nearctic forms 25 are specifically, G subspecifieally and two varietally identical with Palearctic forms. The results of the foregoing study of the Transition and Boreal ant-fauna agree in the main with those derived from other animals and of plants, and suggest the same problems as to the original source of the North American ant-fauna, the meaning of the differences between its western and eastern constituents and of the much greater richness of the former in species, subspecies and varieties. An intensive study of the geographical distribution of any circumscribed group of organisms necessarily involves an appeal to general historical considerations, since no group can be satisfactorily studied as an isolated unit. One is compelled, therefore, to assume an attitude towards certain hypotheses which have been gradually elaborated and are more or less firmly supported by the researches of many workers on many different groups. In assuming such an attitude one is inevitably more or less biased by the particular group or groups with which one is most familiar. Before considering the hypothetical centers of origin and the migrations of the various existing categories of insects and especially of the ants, it seems advisable to determine, if possible, the geological age of these categories. This has been attempted in three different ways: first, by a study of paleontology, second, by a study of present distribution on the supposition that forms with a wide and especially with a wide and discontinuous range are older than forms with a limited, continu- ous range, and third, by a combination of both of these methods. It is evident that the first method is of great importance, the second by itself of comparatively little value and open to many objections, and that the value of the third method depends largely on the paleonto- logical facts to which it may be able to appeal. It is, however, the most comprehensive method and owing to the incompleteness of the paleontological record, the only one that can be resorted to in the study of many groups of organisms at the present time. Our knowledge of fossil ants is rather limited but of great signifi- cance. The earliest known species are those of the Baltic amber, of Lower Oligocene age. Mayr (186S) and I (1914) have described nearly a hundred of these belonging to no less than 43 genera, 19 of which are extinct and 24 still extant, viz: Edatomma (subgen. Rhyti- doponera), Euponcra (subgen. Trachymesopus), Platythyrea, Ponera, Sima, Monomorium, Erehomyrma, Vollenhovia, Stenainma, Aphaeno- gaster, Myrmica, Leptothorax, Dolichoderus (subgen. Hypoclinea), Iridomyrmex, Liometopum. Plagiolepis, Gesomyrmex, Dimorphnmyrmez, Oecophylla, Prenolepis, Lasius, Formica, Pseudolasius and Camponotus. 488 WHEELER. From the Scilian amber, which is of later, Miocene age, Emery (1891) has described 14 ants representing 13 genera, 11 of which are still extant, viz: Ectatomma, Ponera, Cataulacus, Podomyrma (subgen. Acrostigvia) , Aeromyrma, Crematogaster, Tapinoma, Tcchnomyrmex, Plagiolepis, Gesomyrmex and OecophyUa. Heer (1848, 1849) had previously described a number of ants from the Miocene shales of Oeningen and Radoboj, but owing to the imperfectly developed taxonomic categories of his day, referred them to such generalized genera as Formica, Ponera and Myrmica. Mayr (1867), however, examined many of Heer's types from Radoboj and was able to recog- nize among them representatives of the following modern or extant genera: Aphaenoga^ter, Leptothorax, Liometopum, Dolichoderus (sub- gen. Hypoclinca), Lasiiis, Formica, Oecophylla and Camponotus. Among several thousand ants from Florissant, Colorado, also of Miocene age, I am now able to recognize specimens belonging to the recent genera Plicidole, Crematogaster, Aphaenogaster, Liometopuvi, Dolichoderus (subgen. Hypoclinea), Lasius, Formica and Camponotus, in addition to a few extinct genera (e. g. Agroecomyrviex) . It is evi- dent, therefore, that a large number of important ant genera of the present had been developed by early Tertiary times, and as the species representing these genera are quite as highly specialized as their existing congeners, I believe that we must assume that their genera go back at least to the Basic Eocene or even to the Upper Cretaceous. And since these genera clearly represent four of the five subfamilies of living ants, and among them the most highly specialized subfamily, the Camponotinae, we are justified in assuming that the subfamilies of the Formicidae were differentiated during the Mesozoic, probably as early as the Jurassic or Triassic. This assumption is in general accord with the opinions of Emery (1893) and Handlirsch (1913). According to the latter " we know today that by the end of the Cre- taceous all the main groups of insects had been completed, that the species living today arose not later than the Pleistocene and the majority of them in the Pleiocene and in certain cases go back even to the Oligocene. The present genera were certainly nearly all completed in the late Tertiary, many of them already in the Oligocene and per- haps some of them in the Upper Cretaceous." He believes (1909) that the Formicidae as a family could scarcely have originated before the Upper Cretaceous. I am inclined to believe that these estimates, at least as far as the ants are concerned, are too conservative. If I understand Emery correctly, his estimates are somewhat closer to my own, for he is inclined to assign the genera of the oldest subfamily. MOUNTAIN ANTS OF NORTH AMERICA. 489 the Ponerinae, and several Myrmicine genera to the Mesozoic, and many DoHchoderinae and Camponotinae to the early Tertiary. Kolbe (1913), however, comes still closer to my point of view in a very suggestive study of the distribution of certain ancient genera of Coleoptera, an order which can scarcely be much older than tlic Hymenoptera. He calls attention to the fact that if we compare the beetles of Australia and Europe we find that they possess no less than 146 genfera in common, and that owing to the fact that Australia was isolated during the Eocene we are justified in regarding all such genera as of Mesozoic age. I believe that the same conclusion is admissible in the case of other insects and especially in regard to the ants and would hold good also of the genera common to Australia and America. In the following list, including all the known genera of Australian ants, the genera printed in large type are represented also in the Neotropical and Nearctic faunas and those preceded by an asterisk occurred in the Tertiary of Europe or are represented in the living fauna of that continent: SPHINCTOMYRMEX *CERAPACHYS Phyracaces Myrmecia Amblyopone *PLATYTHYREA ACANTHOPONERA Onychomyrmex Paranoraopone Diacamma *ECTATOMMA Bothroponera Odontopoaera *EUPONERA *PONERA Dorylozelus Prodiscothyrea Prionogenys LEPTOGENYS *ANOCHETUS ODONTOMACHUS Aenictus Metapone *Sima *01igomyrmex Pheidologeton *CREMATOG ASTER *SOLENOPSIS *PHEIDOLE Lordomyrma *Vollenhovia *Podomvrma *MYRMECIXA Machomyrma Dacryon *MONOMORIUM *CARDIOCONDYLA *APHAENOG ASTER *TETRAMORIUM Pristomyrmex Triglyphothrix Mayriella ROGERIA Prodicroaspis Promeranoplus Meranoplus 490 WHEELER. Calyptomyrmex *STRUMIGENYS *EPITRITUS Orectognathus Epopostruraa Rhopalothrix *DOLICHODERUS (subgen. HYPOCLINEA) Leptomyrmex Frogattella Turneria *TRIDOMYRMEX *BOTHRIOMYRMEX *TAPINOMA *Technom\Tmex Acropyga *Plagiolepis *Acantholepis (subgen. Stigmacros) Prolasius Melophorus *Pseudolasius Notoncus *Oecophylla Mynnecorhynchus *PRENOLEPIS Opisthopsis Echinopla Calomvrmex *CAMPONOTUS Polyrhachis Of the 75 genera in this hst 31 or 41.3% are known to exist or have existed in Europe and 27 or 36% in America; 37 or 49.3% are unknown in either of these regions, but more than half of them are represented in the Oriental region. As the migration of ants from the latter region into Australia since its isolation has been very much restricted, these genera must also be regarded as of Mesozoic origin. It should also be noted that 21 or 28% of the 75 Australian genera belong to the most ancient and primitive subfamily of the Ponerinae, a group com- parable to the Monotremes and Marsupials among mammals and one which reaches no such proportions in any of the other geographi-- cal regions. I believe, therefore, that we have underestimated the antiquity of the genera of ants and that the great majority of them are of Pretertiary or at the latest of early Eocene development. The same may be true even of certain species of tropicopolitan or cosmo- politan distribution, e. g. Solenopsis gemmata, Odontomachvs haematoda and especially Camponotus (Myrmoturba) maculatiis, which is repre- sented by numerous local races and varieties not only on all the con- tinents but also on many islands (e. g. Hawaii!). There are good reasons for believing, however, that the great majority of existing species and subspecies are of Postmiocene origin. In North America and Eurasia, at any rate, only subspecies and varieties seem to have developed since the Ice Age. This is indicated by the very small number of varieties common to the Nearctic and Palearctic faunas as compared with the number of common species and subspecies (see pp. 485-486). MOUNTAIN ANTS OF NORTH AMERICA. 491 Paleographers agree in characterizing the Upper Jurassic as a period of great continental emergence, warm climate and a cosmopoli- tan flora. During this and the ensuing Cretaceous most of the families and genera of insects, like the flora on which so many of them were vitally dependent, must have assumed their modern facies and have become very widely distributed. According to Osborn (1910, p. 95) the "most memorable fact about the flora is one recently insisted upon by Knowlton (1909), namely that as we pass from the Cretaceous into the Eocene there is no appreciable change in the flora. From this it would appear that there was no secular change of climate; that the temperature was the same." There is nothing to indicate that the insects underwent any profounder change than the plants, so that we are unable to believe that these animals exhibited anything like the catastrophic elimination which occurred in several other groups of organisms both terrestrial and aquatic at the end of the Cretaceous. There is therefore no justification for assuming a close parallel in the course of development of such insects as the ants during the Tertiary with that of the mammals, whose phylogeny during that period was very complicated and greatly accelerated. The repeated migrations of mammals between North America and Eurasia during Cretaceous and Posteocene time were probably paralleled by the ants but we have no precise evidence of such movements. A single land-bridge, the Siberian-Alaskan, which is accepted by all students of geographical distribution, and according to most of them was in existence during the Cretaceous and again from late Miocene to Pleistocene times, is sufficient to account for the present constitution of our North American ant-fauna. Scharff (1907, 1912) and others have adduced considerable evidence in favor of another land-bridge connecting North America with Great Britain and Scandinavia during Pre- glacial and early Glacial time, but others reject this construction though they have not succeeded in accounting for the fauna and flora of Greenland and Iceland and the distribution of many eastern Nearc- tic and western European forms on any other hypothesis. That there was a gradual cooling of the climate from late Eocene to the Glacial Epoch is also generally admitted and the resulting develop- ment of pronounced zonal climates had a very powerful effect, as we know, on the fauna and flora of the northern hemisphere. The elimi- nation of species thus induced over the area covered by the great ice-sheet both in Europe and North America and the southward migration of surviving species away from its border have been so often discussed that I need not dwell on them here. The ants of the 492 WHEELER. Baltic amber and of Florissant, like the plants of the same formations, show \ery clearly the gradual cooling of climate during the early and middle Tertiary. In the latitude of Sweden, where the amber was formed, the climate seems to have been subtropical as early as the Lower Oligocene, since the ants belonging to boreal genera such as Formica, Lasius, Prenolepis s. sir. etc. constitute a dominant compo- nent of the fauna, at least in individuals. During the Miocene the climate of Colorado, as indicated by the Florissant plants, resembled that of the Gulf States at the present time. The ants perhaps indi- cate a slightly cooler and dryer climate, not unlike that now prevail- ing at low altitudes in Colorado or New Mexico. I am inclined to believe, with Scharff , that the extent of the south- ward migration or displacement of organisms beyond the border of the ice sheet during glacial times has been exaggerated by many authors. Still there must have been some displacement and consid- erable extinction. It is at any rate clear that owing to the absence of such a complete barrier to southward migration as the Alps and the Mediterranean, our North American fauna suffered much less severely during the Ice Age than that of Europe. Moreover our fauna has been greatly enriched since the Pleistocene by a northward immigra- tion of numerous neotropical species into the Southern United States by way of Mexico and the West Indies. The neotropical immigrants among ants belong to the Doryline genus Ecitori, to several Ponerine genera {Neoponera, Pseudoponera, Edaiomvia, Lepiogenys and Odonto- machus), to several Myrmicine genera (Pseudomyrma, Cryptocerus, Mcwroinischa, Xenomyrmex, Xiphomynnex, possibly PogoJioviyrmex and especially to the fungus-growing tribe Attini {Atta, Acromyrmex, Trachymyrmex and Cyphomyrmex), to the Dolichoderine genera Forelius, Dorymyrrnex and Iridomyrmex and to the Camponotine genera Brachymyrmex, Prenolepis (subgen. Nylandcria) and Campono- tus (subgen. Myrmothrix, Myrmobrachys and Myrmamblys). Some of these genera {Pseiidoponera, Odontomachus, Leptogenys, Iridomyr- mex) are common to paleotropical regions and at once suggest the question as to whether they originally reached South America during the Cretaceous by way of Antarctica from Australia or came from Asia by way of North America or over other land-connections from otl^er parts of the Old World, and therefore involve a discussion of the hypothetical southern land-bridges, which several recent writers, notably H. von Ihering and Scharff, have been very actively construct- ing in order to explain certain cases of wide and discontinuous distribu- tion among organisms. So far as the Formicidae are concerned I MOUNTAIN ANTS OF NORTH AMERICA. 493 unreserv'edly agree with those who repudiate all such connections, with the exception of the Siberian-Alaskan and possibly the North Atlantic bridges. I am quite unable to find anything in the neo- tropical ant-fauna that makes it necessary to assume former connec- tions of South America with Australia or with Africa. The only genus supposed to be peculiar to Australia and South America is Melophorus, which is represented by numerous species in the former region and to which Forel and Emery referred a few Chilian and Pata- gonian species formerly regarded as belonging to the holarctic genus Lasius. But Emery later showed that the Chilian and Patagonian forms really constitute a distinct subgenus, which he called Lasio- phancs. From a recent study of the Australian species I am convinced that the}^ should be generically separated from the South American species. So far as Africa and South America are concerned, they have no genera in common which have not a much wider distribution in the Palearctic or Oriental regions. Among the numerous writers on geographical distribution who have recently rejected or ignored the speculations of the bridge-builders, I will consider only Kolbe, Handlirsch and Matthew, as they seem to me to have reached conclusions very similar to those suggested by my study of the Formicidae. These writers recall those who, like Allen (1878), Scribner (1882) and Haacke (1887) long ago pointed to the north polar region as the original center of organic distribution, but differ in placing this center in Central or Eastern Asia. Kolbe (1913) calls attention to the vast extent and great permanence of the Asiatic continent during geologic time as contrasted with Europe and selects the region between the Caspian Sea and Eastern China, and especially Turkestan and Thibet, as the most ancient of the sources and reser- voirs of Palearctic animal life. This is indicated by both the mam- mals and the insects. Of the single beetle genus Carabus Central Asia alone possesses 35 endemic subgenera! Europe is merely a zoogeo- graphical appendix of Asia, to which the African, Australian and North American faunas are easily traceable by emigration during the Cre- taceous when there existed a broad Siberian-Alaskan land-bridge. Kolbe does not discuss the origin of the neotropical fauna nor the antarctic and other land-bridges, but Handlirsch (1913) comes to close grips with these constructions in a valuable statistical study of more than 16,000 insect genera, comprising 180,000 species or about one third of the known forms. His results in regard to the distribution of the endemic as contrasted with the more widely distributed genera in the various geographical regions are given in the following interesting table: 494 Of Wallace's regions, the Neotropical, owing to its very large pro- portion of endemic genera, is therefore the most independent and best established, the Nearctic the least. In an examination of 8300 selected genera, Handlirsch finds that only about 4% have a discon- tinuous distribution and would therefore constitute the chief basis for the contentions of the bridge-builders. But it appears that the generic relations between the Neotropical and Ethiopian regions, for which von Ihering constructed his " Archhelenis " land-bridge, are actually feebler than those between the Neotropical and Oriental, or between the Nearctic and Oriental or between the Palearctic and Australian! Furthermore, the Neotropical is really more closely related to the Palearctic than to the African insect fauna. These facts are clearly brought out in the following numbers of genera found to be common to the different regions, after excluding the cosmopoli- tan species: Palearctic and Nearctic 1225 Nearctic and Neotropical 1159 Palearctic and Oriental 1083 Oriental and Australian 754 Oriental and Ethiopian 701 Palearctic and Ethiopian 687 Palearctic and Neotropical 571 Palearctic and Australian 472 Nearctic and Oriental 306 Neotropical and Oriental 259 Ethiopian and Australian 327 Neotropical and Australian 228 Neotropical and Ethiopian 195 Nearctic and Australian 197 Nearctic and Ethiopian 159 MOUNTAIN ANTS OF NORTH AMERICA. 495 The study of such a circumscribed group as the Formicidae would be even more unfavorable to the views of von Ihering and other bridge- builders than the more comprehensive studies of Handlirsch, because the relationships of the ants of South America to those of Africa or Australia would be represented, as I have stated, only by genera of cosmopolitan range or at any rate common to the Palearctic and Oriental regions, from which they could have found their way to the New World over the Behring Sea and North Atlantic land-bridges. Handlirsch summarizes his views on the migrations of forms between the different regions in the following simple diagram, in which S stands for the Neotropical and Ae for the Ethiopian region: Matthew (1915) has reached very similar conclusions from a study of the distribution of Vertebrates and particularly of the mammals. He finds the same fallacies as Handlirsch in the work of the bridge- builders and expresses them in the following paragraphs: " 1. The discontinuous distribution of modern species is again and again taken as proof that the regions now inhabited must have been connected across deep oceanic basins, without considering the possi- bility that it is a remnant of a wider past distribution, or that it is due to parallel evolution from a more primitive type of intermediate distribution, now extinct. Yet so many instances are known where the geological record has furnished proof that one or the other of these explanations applies to cases of discontinuous distribution, that it would seem that these ought to be the first solutions of the problem to be considered, and that in view of the known imperfection of the 496 WHEELER. geologic record, mere negative evidence is not sufficient to cause them to be set aside. "2. No account is taken of faunal interchanges often much more extensive, which would presumably have taken place if the land- bridges assumed had existed, but which have not taken place. It may here be urged that this too is negative evidence. But the nega- tive evidence derived from an appeal to the geological record is weak, not per se, but because of the demonstrated imperfection of the record. On the other hand, there are many instances where a land-bridge is well proven, and in these cases it is not a few scattered exceptions, but an entire fauna that has migrated, subject only to the restrictions imposed by climatic or topographic barriers of other kinds." In accounting for the present discontinuous distribution of many ancient and primitive forms Matthew seems to me to have made good use of a principle which seems to have been first suggested by Haacke (1887). This writer called attention to the fact that at the present time the most primitive types of the various groups of animals are mostly confined to the tropics and the southern hemisphere. This can be most readily explained on the supposition that the situations in which such forms now live are not their original habitats but those to which they have been relegated by more recent and more specialized forms evolving and usurping their places in the territory originally occupied by the group. Hence the oldest and most primitive members of a group come to be found today at the periphery of its range and the more recent and specialized forms in or near its center. Clark (1915) has reached the same conclusion from his study of the dis- tribution of the Onychophora. He says: "Any animal type, once evolved, will extend itself immediately in every direction as far as the natural barriers to its dispersal; a more specialized form (a dominant type) of the same animal, better fitted for the conditions under which it lives, will sooner or later be evolved somewhere in the central, or more favorable portion of the territory inhabited by the original type; this new type will at once extend itself as did the original type; but in the meantime there may have arisen certain barriers, which the second type cannot cross and beyond which, therefore, the first type is secure. Up to these barriers — high mountains, deserts, newly formed arms of the sea, or whatever they may be — the second type will gradually supplant the first, as a result of its better economic equipment and more perfect physical resistence, and the advantage which this better equipment and resistance give it in the struggle for existence. Thus we shall eventually find a specialized type beyond MOUNTAIN ANTS OF NORTH AMERICA. 497 the limits of which occurs a more generalized type of the same organ- ism. The subsequent evolution of additional types, which will most frequently occur at or near the so-called center of distribution as a natural result of the greater facility for adaptation due to the greater distance apart of the physico-economic barriers and tlie consequently greater radius of each type, will result in the gradual formation of a dispersal figure which would be ideally represented by a series of con- centric circles, each of the circles representing a barrier, the small central circle enclosing the most perfected type and the peripheral band the most generalized, the intervening areas including intermedi- ate types increasing in specialization toward the center." The Formicidae show in a very striking manner the relegation of the most primitive forms to the tropics and southern hemisphere and especially to the Neotropical, Oriental and Australian regions. As all of these forms are exquisitely thermophilous and stenothermal, whereas the Palearctic and Nearctic faunas and particularly the forms peculiar to the mountains consist of more specialized, stenothermal and psychrophilous species together with a small number of eury- thermal ubiquists, we are led to believe that the development of zonal climates during the Tertiary has been the essential factor in determin- ing the distribution of the present world-wide distribution of ants. The mountain faunas are therefore of comparatively recent origin and this is particularly true of that of the Rocky Mountains, to judge from the large number of subspecies and varieties, most of which have, in all probability, developed since the Pleistocene. The Rocky Moun- tains as an independent center of formation of new forms contrast markedly with the Alps and Himalayas, for there are relatively few ants peculiar to the latter and especially to the Alps. This may be attributed to geological conditions. Geologists maintain that the Rocky Mountains began to be elevated as early as late Cretaceous time and by the Eocene had attained altitudes of 4000 to 5000 feet. They continued to rise during the Tertiary Period to altitudes of 13,000 to 14,000 feet, with a corresponding elevation of the bases between them and considerable erosion of their summits. The Alps however, did not appear till the close of the Oligocene and only during the Miocene were the Himalayas uplifted. The Alpine area, more- over, was surrounded by water till the Miocene when it became joined by a broad land-connection with Central Asia. Its connection with France by means of another land-connection is said to have occurred at the end of the Miocene. These conditions, together with the later extensive glaciation of the Alps, must have been very potent factors 498 WHEELER. in preventing the development of an indigenous ant fauna. On the other hand the Rocky Mountains occupy a very hirge area and were much less affected by the unfa\'orable climate of the Ice Age. They therefore remained as a preserve of Pleiocene species and during more recent times became a center of origin of many races and varieties. For evidence in support of this contention we have only to compare the Nearctic and Palearctic forms of the genera Myrmica, Leptothorax, Losius, Formica, Polyergiis and Campouofus. I advanced the opinion that the Rocky Mountains were probably the center of origin of the genus Forinica in my paper on this group (1913), but I now accept Handlirsch's view that not only the genus Formica, but the whole family Formicidse had its origin during the Mesozoic in Eurasia and believe, with Kolbe, that Central or Eastern Asia is, as seems to be the case with so many other groups of organisms, the most likely spot in which to seek the origin of the ants. The views of Matthew and Clark on the development of the specialized forms in the center of the geographical range of a group and the relegation of the older and more primitive forms to the periphery of that range, appear at first sight to support my former contention, but it now seems to me to be more probable that the Rocky Mountains constitute only a secondary, more recent center of speciation, and that they are much more important as a region of conservation. It may be noted in this connection that Japan is evidently a similar secondary center of speciation for the same genera, since in that country the common holarctic species of Myrmica, Lasius, Formica, Polycrgus and CampO' notus have developed several peculiar subspecies and varieties. The same is true of the Eastern United States, which are also characterized by the development of endemic forms of Myrmica, Formica, etc. This brings us, finally, to the problem with which we started, the pronounced difference between the ant faunas of western and eastern North America, a difference very similar to what has been so often noticed in other groups of organisms. It may be readily attributed to a difference in survival after the glaciation of the northern portion of the continent, since the ice-sheet is known to have advanced con- siderablv further south in the eastern than in the western half of the continent, while the Gulf of Mexico formed an impassable barrier to a directly southward emigration of species. Hence we should expect a much more meager survival of species in the Eastern than in the Western United States. The differences of character in the endemic forms of the two regions, however, must be due to other conditions, some of which were undoubtedly preglacial, while others were as clearly MOUNTAIN ANTS OF NORTH AMERICA. 499 postglacial. If we may judge from the Florissant deposits, the North American ant-life of Miocene times was poorer in species than that of Europe, but we must bear in mind that the Florissant locality is a very limited and ele^•ated area and that the preserved ants are nearly all males and females which happened to fall into a small lake during their nuptial fligh.t and after sinking to the bottom became embedded in volcanic sediment. Many of the species became extinct, but some of them, notably those of the genera Aphacnogaster, Lasius and Liome- topuin, were undoubtedly very closely related to forms of the same genera still living in Colorado. To the descendants of this Miocene fauna there was added during the Pleiocene a number of forms by immigration from Asia over the Siberian-Alaskan land-bridge, proba- bly at the same time and by the same route as the Strepsicerine and Hippotragine antelopes. Probably, too, certain North American ants passed into Asia at the same time, just as seems to have been the case with the camels. Emery has recorded the occurrence of Camponotus herculeanus subsp. pennsylvanicus in Siberia and Burmah, and the closely related C. japonicus was originally described by Mayr as a mere variety of that subspecies. Probably such species as Aphacnogaster suhterranea, Mijrmica lobicornis, Leptothorax vniscorum, some form of the subgenus Neomyrma closely related to the Eurasian rubida and the ancestor of A^. mutica, hunteri and aldrichi, together with several species of Formica, notably cinerea, rufibarbis, rufa, trun- cicola and Polyergus rufesccns, first entered North America during the Pleiocene. Even at the present time few of these species have suc- ceeded in extending their range to the Atlantic States. The origin of the peculiarly eastern forms is more obscure. Probably a number of them are Mesozoic and early Tertiary survivors, notably the Pone- rinae, and the species of Strumigenys, Myrmccina and Aphacnogaster. Others may have come from Europe over the North Atlantic land- bridge during the late Tertiary and have given rise to such forms as Formica ulkei, exsectoides, and pallidcfulva and Camponotus castaneus. Some of these have migrated westward as far as the easternmost ranges of the Rocky Mountains but none has reached the Pacific Coast Eurythermal ubiquists like Tapinoma sessile, Prenolepis imparis and Formica fiisca may have existed in North America since the Oligocene or Eocene. F. fusca and P. imparis are, as I have shown (1914), almost identical with F. flori and P. henschei of the Baltic amber. That elements derived from such various sources and migrations, probably separated by long periods of time, should have gradually evolved a number of subspecies and varieties in the localities to which 500 WHEELER. they were at first confined, is only what might be expected. And that such varieties and subspecies should be much more numerous in the Rocky Mountains than in the Eastern States is also to be expected, when we consider the much greater variety of physical conditions in that region. The high mountains running north and south through many degrees of latitude, with very high timber and snow lines and often broken into isolated ranges separated by arid basins or "parks," sometimes of great extent, constitute a much more favorable territory for the production of endemic races and varieties than the compact east and west massif of the Alps with their low timber and snow lines and narrow valleys. Some ver}^ short mountain ranges, especially in Arizona, New Mexico and Western Texas are, in fact, quite insular, being completely surrounded by the desert from which they rise, and like islands have developed numerous endemic, or precinctive forms. This is very clearly seen in the Huachuca Mountains of Arizona, which are inhabited by several ants and other insects not known to occur in any other localities. The Coast Range and Sierra Cascade Ranges have also each developed a number of endemic forms. Unfortu- nately we are unable at the present time to appreciate the precise character and extent of this endemicity in our western mountains, because our knowledge of the distribution of any single insect group in any one of the various ranges is very fragmentary. This is equally true of the Appalachian System (White Mountains, Adirondacks, mountains of North Carolina and Georgia). Certainly no more inter- esting work could be undertaken by our taxonomic entomologists than a detailed and systematic survey of the various groups of insects in all these ranges after the manner of the fine surveys of the distri- bution of vertebrates and woody plants by Dr. C. H. Merriam and his collaborators. MOUNTAIN ANTS OF NORTH AMERICA. 501 List and Descriptions of Western Mountain Ants. Myrmicinae. 1. Monomorium minimum Buckley. The typical form of this species, which is common in Texas and the Atlantic States at lower elevations and south of New England, has been taken by Prof. C. F. Baker in Ormsby County, Nevada, on the eastern shore of Lake Tahoe. I have found it in Arizona and Colorado and Dr. W. M. Mann collected it in the mountains of Hidalgo, Mexico. 2. Monomorium minimum subsp. ergatogyna Wheeler. Known only from Catalina Island, Cala., where it was taken several years ago by Prof. C. F. Baker. 3. Monomorium minimum, subsp. compressum Wheeler. Taken by Dr. \N. M. Mann at Guerrero Mill, Hidalgo, Mexico. 4. Monomorium minimum subsp. cyaneum Wheeler. A beautiful metallic blue form from the same locality as the preced- ing. 5. Solenopsis molesta Say. The typical form of this species is abundant throughout the East- ern United States and Southern Ontario. It occurs also, but more sporadically, in the mountains of Colorado and New Mexico at alti- tudes below 8000 ft. 6. Solenopsis molesta var. validiuscula Emery. Originally described from Los Angeles and San Jacinto, California. I have taken it in the Santa Inez Mts. near Santa Barbara in the same state, and Dr. Mann has give me specimens which he collected at Wawawai, Washington. 7. Solenopsis molesta var. castanea Wheeler. A dark color variety originally described from Woodland Park, in the Ute Pass, Colorado (Wheeler). 8. Myrmecina graminicola Latr. subsp. americana Emery. A rather rare ant, occurring in rich, shady woods in the Eastern States and as far west as Texas and the Grand Canyon, Arizona. 502 WHEELER. 9. Myrmecina graminicola subsp. amerkana var. hrevispinosa Emery. In distribution this form is similar to the preceding. I have taken it as far west as New Braunfels, Texas, and have seen specimens col- lected by Mr. E. S. Tucker at Piano in the same state. 10. Myrmecina graminicola subsp. texana Wheeler. Known only from Austin, Texas, where I found it many years ago in moist places in the canyons of the Edwards Plateau. 11. My r mica brevinodis Emery. The typical form of this species is common in the Transition Zone of Colorado, about Colorado Springs, Denver, Boulder, Buena Vista, etc. 12. Myrmica brevinodis var. brevispinosa Wheeler. Known from New Mexico and Colorado. 1.3. Myrmica brevinodis var. frigida Forel. The types of this variety were taken by Whymper in the Ice River Valley, British Columbia (5000 ft.). 14. Myrmica brevinodis var. sulcinodoides Emery. British Columbia: Hector, Carbonate and Spillimachen R., Selkirk Mts. (C. J. Bradley); Field and Yoho Pass, Emerald Lake (Wheeler). Alberta: Lake Louise (Wheeler). Colorado: Rico, 10,000 ft. and Hayden Peak, 10,000 ft. (E. J. Osier); Boulder and Ward (W. W. Robbins); Lost Lake, Eldora, 9500 ft. (D. M. Andrews). California: Lake Tahoe, 6000 ft. (Wheeler). This variety is so much like the typical European M. sulcinodis Nyl. that one is inclined to regard brevicornis as merely a subspecies. The form described by Forel as brevinodis var. whymperi from Vermil- ion Pass, Alberta, is, so far as I am able to judge from two cotypes received from Prof. Forel, merely sulcinodoides. For a description and further citations of localities of this variety from Utah, Colorado and New Mexico, see my revision of the forms of brevinodis in Bull. Wis. Nat. Hist. Soc. 5, 1907, p. 73 et seq. The workers from Lake Tahoe have the epinotal spines rather short and perceptibly curved down- ward at the tips. It does not seem desirable to regard them as repre- senting a distinct variety. MOUNTAIN ANTS OF NORTH AMERICA. 503 15. Myrviica brcvinodis var. deccdens Wheeler. Colorado: Biiena Vista, 7900 ft. (type locality) and Florissant, 8500 ft. (Wheeler). New Mexico: Pecos Mts., San Miguel County (Mitchell). The workers from New Mexico are considerably darker than the types and may prove to belong to a distinct variety. 16. Mijrmica brcvinodis var. alaskensis var. nov. JVorker. Length 3.5 mm. Resembling the variety- sulcinodoidcs but smaller and of a different color. Head black above; thorax, pedicel and gaster castaneous; mandibles, antennae and legs brownish yellow. Antennae slightly thicker at the base than in sulcinodoidcs. Rugae on the clypeus very coarse, much fewer in number (only 8) than in other forms of the species; frontal area distinctly outlined, subopaque and very finely punctate, not longitudinally rugulose. Rugae on the sides of the head coarsely reticulate, not longitudinal, those on the thorax and pedicel much as in sulcinodoidcs but a little finer; surface of head, thorax and pedicel a little more opaque. Epinotal spines somewhat shorter than the base of the epinotum, curved downward at their tips. Summit of petiolar node distinctly nlore rounded than in sulcinodoidcs and transversely rugose, postpetiolar node less convex behind. Pilos- ity like that of sulcinodoidcs. Described from eight workers taken at Seward, Alaska by Mr. F. H. Whitney. 17. Myrmica brcvinodis var. sidmlpina Wheeler. British Columbia: Hector, Field and Carbonate (J. C. Bradley); Emerald Lake (Wheeler). Alberta: Banff (Wheeler); Jasper (C. G. Hewitt). Washington: Orcus Island (W. M. Mann). This variety, originally described from Florissant, Colo., forms flourishing colonies under logs and stones in moist, sunny places. I found it very abundant on the southern slope of Tunnel Mt. at Banff. It closely resembles the eastern var. canadensis Wheeler, but the wings of the male and female are whitish hyaline throughout and not infus- cated at the base. The workers of certain colonies present transitions in color to the ^■ar. sulcinodoidcs, but this forms smaller colonies and prefers higher elevations. 18. Myrmica m erica n a Wheeler. This species, related to our eastern M. punctiventris Roger, was taken by Dr. Mann at Guerrero Mill, Hidalgo, Mexico. 504 WHEELER. 19. Myrmica scahrinodis Nyl. sulisp. Johicornis Nyl. var. glaciaUs Forel. Alberta: Vermilion Pass, t^pe locality (Whymper); Lake Louise and Moraine Lake, Valley of the Ten Peaks (Wheeler). British Columbia: Emerald Lake (Wheeler); Carbonate and Prairie Hills, Selkirk Mts. (J. C. Bradley). Montana: Helena (W. M. Mann). Utah: Salt Lake County (R. V. Chamberlin). Colorado: Florissant, Ute Pass, Cheyenne Canyon and Manitou (Wheeler) ; Creede Co. 8844 ft. (S. J. Hunter) ; Boulder (P. J. Schmitt); Pikes Peak, 10,000 ft., Willow Creek and West Cliff, 7864 ft. (T. D. A. Cockerell). New Mexico: Harvey's Ranch, Las Vegas Range, 10,000 ft. (E. L. Hewett); Beulah, 8000 ft. (T. D. A. Cockerell). Arizona: San Francisco Mts., 13,000 ft. (W. M. Mann); Coconino Forest, Grand Canyon (Wheeler). Forel described this form from worker specimens as a variety of the typical scahrinodis, but has more recently placed it under the subsp. schencki Emery. During the summer of 1915 I found the males and females in many nests in British Columbia and Alberta and these phases show unmistakably- that glacialis must be regarded as a form of lohicornis, a subspecies common in the Alps and Northern Europe but not hitherto known to occur in America. The antennal scapes of the male glacialis are strongly bent at the base and fully § as long as the funiculus. They are therefore only a little shorter than in typical lohicornis. The other differences are equally insignificant. The glacialis male is a little smaller and has somewhat shorter epinotal teeth, the sculpture of the head and thorax is somewhat feebler so that the surface is more shining. The female is also somewhat smaller than the female of the typical form, its head and thorax are more shining and less coarsely sculptured, and the thorax and pedicel are darker, the angles at the base of the antennal scapes decidedly smaller. The worker specimens from the Grand Canyon, San Francisco Mts. and Boulder have the antennal lobes large and more flattened, much as in the typical lohicornis. The specimens from Helena are consid- erably paler and colored like the eastern sabuleti, but the greater length of the antennal scape in the male shows that they should be placed with lohicornis, although they may represent a distinct variety. 20. Myrmica scahrinodis subsp. schencki Emery \'ar. fahoensis var. nov. MOUNTAIN ANTS OF NORTH AMERICA. 505 Worker. Length 3.3— i mm. Small; antennal scapes geniculately bent at the base and at the flexure with a small rounded lobe, appearing as an acute tooth when the scape is seen from the side. Frontal area very distinct, triangular. Frontal carinae large, lobular. Epinotal spines slightly shorter than the base of the epinotum, as long as their distance apart at the base, rather slender, distinctly curved downwards at their tips. Petiole in profile blunt and rounded above. Head, thorax and pedicel very coarsely and in the main longitudi- nally rugose, the surface subopaque; frontal area opaque, finely and densely longitudinally rugulose; concavity of epinotum smooth and shining like the gaster. Hairs rather long, abundant and suberect on the body and legs as in the typical schencki var. evierijana Forel. Head and gaster black; mandibles, antennae, thorax, petiole and post-petiole deep brownish red; legs slightly more yellowish red. Female (dealated). Length 4.5-5 mm. Very similar to the worker; pronotum transversely, mesonotum and scutellum strongly, pleurae more feebly longitudinally rugose; petiole and postpetiole longitudinally rugose above, densely and finely punc- tate on the sides and below as in the worker. Color like that of the worker, except that the thoracic dorsum and some spots on the pleurae are black. Male. Length 3.5^ mm. Antennae very short, the scapes especially, which are feebly bent at the base and not more than three times as long as broad and shorter than the three basal funicular joints together; club 4-jointed. Frontal area large, distinct, triangular. Sculpture and pilosity much as in the var. evieryana. Color dark piceous brown; head black; mandibles, tarsi and articulations of legs brownish yellow; palpi whitish. Wings pale hyaline throughout, not infuscated at the base as in emeryana. Described from numerous workers, several males and two females from several localities about Lake Tahoe (Tallac, Angora Lake, Glen Alpine Springs, Fallen Leaf Lake). The colonies are small and nest under stones in shady places. 21. Myrmica scahrinodis subsp. schencki var. inonticola var. noA'. Worker. Length 3-3.5 mm. Differing from the vars. emeryana and .iahoensis in its smaller size, in color and in the shape of the antennal scapes, which are rectangu- larly bent at the base and furnished at the flexure with a large, rounded, 506 WHEELER. shovel-shaped, transverse lobe, which is prolonged as a low membran- ous ridge for a short distance along the posterior edge of the joint. Frontal carinae suberect; frontal area small but distinct, triangular. Epinotal spines shorter than the base of the epinotum and than their distance apart at the base, straight, slender and acute. Sculp- ture of the mandibles, head, thorax and pedicel sharp but rather loose and the punctuation of the interrugal spaces very shallow, so that the surface is much more shining than in the other varieties of schencki. Rugae of the pro- and mesonotum very coarse, vermiculate, indistinctly longitudinal. Middorsal portion of postpetiole rather smooth and shining, somewhat as in the var. dctritinodis Emery. Pilosity rather long, abundant, coarse, erect and blunt on the body, appressed on the legs. Color brownish yellow; scapes and legs of a clearer, paler yellow; head more brownish above; first gastric segment dark brown. Male. Length 3.8-4.9 mm. Antennae much as in the var. tahoensis, the scape being distinctly shorter than the three basal funicular joints together. Surface of body shining, feebly sculptured; head finely and densely punctate, with indistinct rugae; the rugae on the thoracic dorsum also very faint. Protuberances of epinotum very blunt. Color brown; head darker; mandibles, thoracic sutures, margins of gastric segments, antennal clubs, legs and tarsi, except the middle portions of the femora and tibiae, brownish yellow. Described from a dozen workers and nine males taken by myself at Buena Vista, Colorado. This is a very distinct form, which in the larger lobe of the antennal scapes approaches the typical European schencki more closely than do either of the varieties tahoensis or emery ana. There are, however, in the Eastern States one or more large, dark, undescribed varieties which have a similar extensive antennal lobe. 22. Myrmica {Neomyrma) bradleyi Wheeler. California: Glacier Point, Yosemite, 8000 ft. and Tallac, Lake Tahoe 6000 ft. (Wheeler). This form was recently redescribed by Forel as Aphaenogasfer (Neo- 7)iyrma) calderoni from specimens taken by Calderon in the Lake Tahoe region. The types were taken by Prof. J. C. Bradley in Alta Meadow, Tulare Co., Cala., at an altitude of 9500 ft. It nests under stones in rather dry, sunny places and in habits closely resembles M. {N .) mutica Emery. The localities for this and two other species are here MOUNTAIN ANTS OF NORTH AMERICA. 507 transcribed from my recent paper on the American species allied to M. rubra Latr. (Psyche, 21, 1914, pp. 118-122). 23. Myrmica {Neomyrma) mufica Emery. Colorado: Denver; type locality (E. Bethel); Colorado Springs, Salida, Buena Vista and Wild Horse, 6000-7000 ft. (Wheeler) ; Canyon City (Rev. P. J. Schmitt). New Mexico: (Ern. Andre). Utah: Salt Lake County (R. V. Chamberlin), as the host of the peculiar xenobiotic ant, Symniynuica chamberlini W^heeler. Washington: Olympia (T. Kincaid); Ellensburg and Pullman (W. M. Mann). Alberta: McLeod (C. G. Hewitt). British Columbia: Dog Lake, Penticton (C. G. Hewitt). 24. Myrmica {Neomyrma) aldrichi Wheeler. Idaho: Moscow (J. M. Aldrich). 25. Myrmica (Neomyrma) hunteri Wheeler. Montana: Madison R. near Beaver Creek, 7500 ft. (S. J. Hunter), 26. Leptothorax andrei Emery. Originally described from California. I possess several workers taken by Dr. W' . M. Mann at Palo Alto in that state. 27. Leptothorax eldoradensis W'heeler. Taken on Mt. W'ilson near Pasadena by Prof. J. C. Bradley. 28. Leptothorax schmitti Wheeler. Known only from Canyon City, Colo. 29. Leptothorax neomexicanus Wheeler. Described from Manzanares, New Mexico. 30. Leptothorax nitens Emery. Known from Utah, California and Colorado. 31. Leptothorax nitens var. heathi Wheeler. Known only from California. 32. Leptothorax nitens var. mariposa var. nov. Worker. Resembling the var. heathi in being brown, with yellow legs and antennae, but the thorax is opaque and densely punctate 508 WHEELER. throughout, hke the petiole and postpetiole. The punctures are decidedly coarser than in this variety and the typical form. The tips of the antennal scapes nearly reach the posterior corners of the head, being separated from them only by a distance equal to the greatest transverse diameter of the scape. Several workers found nesting under the edges of stones in dry places in Tenaya Canyon, Yosemite Valley, Cala. 33. Leptothorax nitens subsp. occidentalis "Wheeler. Described from Friday Harbor, Washington. 34. LeptotJiorax vieJanderi Wheeler. Taken on Moscow Mt., Idaho by Prof. A. L. Melander. 35. Leptothorax furuncuhis Wheeler. Taken in Williams Canyon, near Manitou, Colo, at an altitude of 7500 ft. 36. Leptothorax tricarinatus Emery. Described from a single worker specimen taken by Pergande at Hill City, South Dakota. I have not been able to recognize it among my specimens of Leptothorax.. 37. Leptothorax nevadensis Wheeler. Described from King's Canyon, Ormsby County, Nevada, where it was taken by Prof. C. F. Baker. This locality is on the eastern shore of Lake Tahoe. 38. Leptothorax nevadensis subsp. rudis subsp. nov. Worker. Length 2.6-3.3 mm. Distinctly larger and more robust than the typical nevadensis and much more coarsely sculptured. Funicular joints 2-8 distinctly broader in proportion to their length. Head subopaque, finely and densely longitudinally rugose, with punctate interrugal spaces and sometimes with an interrupted shining median line. Frontal area shining, very finely striated. Mandibles coarsely punctate, striated at their bases. Thorax and petiole coarsely punctate-rugose, the rugae on the pleurae and often also on the pro- and epinotum longitudinal, on the mesonotum often vermiculate. Declivity of epinotum densely punctate and as opaque as the remainder of the thorax (more shining in the typical form). Postpetiole densely punctate and opaque. The epinotal spines are much stouter and blunter, and the petiolar MOUNTAIN ANTS OF NORTH AMERICA. 509 node is much less compressed anteroposterior!;^', its posterior surface being much more convex than in typical nevadensis. The color is considerably darker, the body being castaneous, with the head and gaster, except its incisures, blackish, the mandibles, clypeus, antennae and legs yellowish brown, the femora infuscated in the middle. Pilos- ity as in the t^'pical form. Female (dealated). Length: 3.5 mm. Smaller than the female of typical nevadensis, with longer and more slender epinotal spines and the funicular joints 2-8 shorter. Sculp- ture of the head, thorax and petiole a little coarser. Petiolarnode like that of the worker. In the typical form it is much compressed antero- posteriorly and has a sharp, transverse superior border. There is very little difference in color between the two forms. Described from numerous workers and a single female taken from small colonies nesting under the edges of stones in Tenaya Canyon, Yosemite Valley, Cala. Seven workers from Angora Peak, 8600 ft., near Lake Tahoe, Cala., though differing in certain details of sculp- ture are nevertheless referable to this subspecies. 39. Leptothorax rugaiulus Emery. South Dakota: (Rei'gande). Colorado: (Pergande); Cheyenne Canyon, near Colorado Springs (Wheeler). Washington: Seattle (T. Kincaid). Montana: Helena (W. M. Mann). Study of much more material of this form and its varieties than I possessed when I wrote my " Revision of the North American Ants of the Genus Leptothorax" (Proc. Acad. Nat. Sci. Phila., 1903, pp. 215-260) convinces me that rugaiulus is really a distinct species, as Emery maintained, and not a subspecies of curvispinosus Mayr. The latter is the most generally distributed and abundant Leptothorax in the Eastern and Central States as far west as Missouri, but rugatidus and its varieties are confined to the W^estern States. The two forms also differ in habits, rugaiulus and its varieties nesting under stones and curvispinosus in hollow twigs and old galls. 40. Leptothorax rugatulus var. cockerclli W^heeler. New Mexico: Las Vegas Hot Springs, type locality (T. D. A. Cockerell). Arizona: Miller, Carr and Ramsav Canvons, Huachuca Mts. (Biedermann, Mann and Wheeler). 510 WHEELER. 41. Leptothorax nigatulus var. mediorujus var. nov. Worker. Length 2.5-3 mm. A little larger, much more coarsely sculptured and of a much deeper color than the var. rorkercUi and the subsp. anncctcns. Upper surface of head and gaster black; mandibles, clypeus, antennse, thorax, petiole, postpetiole and a spot at the base of the first gastric segment ferrugi- nous red; margins of gastric segments yellowish; legs yellowish brown, the femora infuscated in the middle. Rugosity of head, thorax and petiole coarse; head but slightly shining; thorax, petiole and post- petiole opaque, densely punctate. Declivity of epinotum transversely rugulose. Epinotal spines a little stouter but not more curved than in the typical rugatuJus. Female. Length 3.5 mm. Decidedly larger than the female of corkerelli, with the body very dark brown, the antennae, mandibles, legs and incisures of the gaster light brown. Surface of head, thorax and pedicel quite as coarsely sculptured as in the worker and much less shining than in cockerclH and the typical rugatulvs. Wings whitish hyaline, with nearly colorless veins and pale brown stigma. Described from many workers and three females from several colo- nies found near Lake Tahoe, Cala. (Tallac, Glen Alpine) and about Camp Curry in the Yosemite Valley. A series of workers and two winged females taken by Prof. J. C. Bradley at Volcano Creek in Southern California also belong to this form. 42. LcpiotJiora.x rugatidits Emery subsp. anncdens Wheeler. The four cotype workers taken at Boulder by Rev. P. J. Schmitt remain the only specimens I have seen of this form. 43. Leptothorax nigatidus subsp. brunnescens subsp. nov. Worker. Length 1.6-2 mm. Decidedly smaller than the preceding forms of the species and much more feebly sculptured, so that the surface of the head, thorax and pedicel is distinctly shining. The epinotal spines are shorter than their distance apart at the base, very feebly curved and slightly deflected at their tips. The postpetiole is nearly twice as broad as long, with prominent, but rounded anterior corners. The petiolar node seen from above is as broad as long, and as in the other forms broader behind than in front. In the other forms the segment is considerably longer. The color is dull yellowish brown, with the upper surface of the head and gaster, the summits of the petiolar and post- petiolar nodes and the middle portions of the femora darker brown. MOUNTAIN ANTS OF NORTH AMERICA. 511 Described from twenty workers taken by Dr. S. J. Hunter in Creede County, Colorado, at an altitude of 8844 ft. 44. LeptotJiorax (Mychothorax) muscorum Nyl. var. sordidus Wheeler. Colorado: Boulder (P. J. Schmitt). 45. Leptothorax (Mychothorax) muscorum var. septentrionalis var. nov. Ifor/iTr. Length 2.5 mm. Resembling the var. sordidus, but with the head and gaster dark brown or black above, the paler portions of the body of a deeper and more ferruginous red and the rugosity and punctuation decidedly coarser, so that the head, thorax, petiole and postpetiole are nearly opaque. The petiolar node is blunter and more rounded above in profile than in sordidus and the typical viuscorum of Europe. Female. Length 2.9 mm. Dark brown; head black; venter yellowish, much of the pleurae lower surfaces of petiole and postpetiole, mandibles, legs and antennae, except the clubs, paler brown. Thorax subopaque, densely punctate, pronotum transversely, mesonotum longitudinally rugulose. Wings white, with colorless veins and brown stigma. Pilosity much as in the worker. Male. Length 2.6-3 mm. Black, legs and incisures of gaster dark brown. AVings as in the female. Head, thorax, petiole and postpetiole subopaque, densely rugulose-punctate. Pilosity abundant, short and white. Described from numerous specimens of all three phases, which I took from several colonies nesting under stones on the southern slope of Tunnel Mt. at Banff, Alberta, a series of workers collected by Dr. C. Gordon Hewitt at Sulphur Springs, near Banff and a few workers which I found in the Yoho Pass, near Emerald Lake, British Columbia. At first sight this ant closely resembles L. rugatulus var. mcdiorufus but it can be readily distinguished by the feeble transverse mesoepino- tal impression and faintly indicated promesonotal suture. 46. Leptothorax (Mychothorax) acervorum Mayr subsp, canadensis Provancher. Washington: Olympia (T. Kincaid). Colorado: Florissant (Wheeler); Ward and Pikes Peak, 10,000 ft. (T. D. A. Cockerell). 512 WHEELER. Utah: Little Willow Creek, Salt Lake Co (R. V. Chamberlin). Maine: Orono (H. H. Severin). New Hampshire: Franconia and summit of Mt. Washington (Mrs. A. T. Slosson). This species was originally described from Canada. The following smaller and darker variety is also widely distributed through the Can- adian Zone but seems to be rare and local : 47. Leptothorax (MychotJiorax) accrvorum subsp. canadensis var. convivialis Wheeler. Wisconsin: Milwaukee, type locality (Wheeler). New Mexico: Beulah, 8000 ft. (F. W. P. Cockerell); Top of Las Vegas Range, 11,000 ft. (T. D. A. Cockerell). Connecticut: Colebrook (Wheeler). Nova Scotia: Digby (J. Russell). Newfoundland: Spruce Brook. This form was described as L. canadensis subsp. ohscurus by Viereck in a paper on the Hymenoptera of Beulah New Mexico (Trans. Amer. Ent. Soc. 29, 1903) which appeared a month later than my revision of the species of Leptothorax. 48. Leptothorax (Mychothorax) acervorum subsp. canadensis var. kincaidi Pergande. Four workers and a dealated female taken by Mr. F. H. Whitney on the Upper Kugarok River, north of Nome, Alaska (65°!) are clearly referable to this variety, originally described from Metlakahtla. Both phases are larger (worker 3 mm.; female 4 mm.) and more coarsely sculptured than our other North American forms. In my workers the reddish brown thorax has a black crescent on the pronotum and the upper surface of the epinotum and the petiole and postpetiole are of the same color. The epinotal spines are long, thick and blunt, the antennal scapes reach only a little more than half the distance between the eyes and posterior corners of the head. The hairs on the legs are short, coarse and suberect. 49. Leptothorax {Mychothorax) acervorum subsp. canadensis var. yankee Emery. British Columbia: Glacier (Wheeler); Rogers Pass and Prairie Hills, Selkirk Mts. and Carbonate (J. C. Bradley). Alberta: Lake Louise and Moraine Lake, Valley of the Ten Peaks (Wheeler). MOUNTAIN ANTS OF NORTH AMERICAN. 513 Colorado: Boulder (P. J. Schmitt and W. W. Robbins). South Dakota and Utah: (Emery). Michigan: Washington Harbor, Isle Royale (O. McCreary). At Glacier and Lake Louise I found several colonies of this ant nesting under stones in rather damp places. The worker form, origi- nally described from South Dakota, Utah and Colorado, differs from the typical canadensis and the preceding varieties in its somewhat finer sculpture and paler color, the mandibles, antennae, except their clubs, the thorax, pedicel and legs being reddish brown or red, the femora infuscated in the middle. The epinotal spines are rather long and pointed. The male measures 4 mm. and is distinctly larger than the worker (2.5-3 mm.) and only slightly smaller than the typical acervorum, from which it is almost indistinguishable. Comparison with Swiss specimens shows that the x\merican variety has a darker pterostigma and smaller epinotal protuberances. The female is somewhat smaller and darker than the female of the typical acervorum. 50. Lcptothorax (Mychothorax) acervorum subsp. canadensis var. calderoni Forel. I have taken numerous workers and females of this form in the type locality (about Lake Tahoe, Cala.), where it is common in little nests in the bark of large pine logs and stumps, often in plesiobiosis with Camponotus herculeanus var. modoc. The worker has the color of the var. yankee. According to Forel the antennal scapes are longer than in canadensis, reaching nearly to the posterior corners of the head, but my specimens show considerable variation in this particular. Nor do I find that the worker calderoni is larger than the European ■acervorum, though it is larger than the var. yankee. My workers vary considerably in size, from 2.5-3.5 mm. The main difference which I detect between yankee and calderoni is in the proportions of the pro- mesonotum, the length of this region in the latter form between the cervical ridge of the pronotum and the mesoepinotal suture being more than \\ times the breadth of the pronotum through the humeri, whereas in yankee it is distinctly less. Sculpture and pilosity are very similar in the two forms. 5L Lcptothorax (Mychothorax) acervorum subsp. crassipilis subsp. nov. Worker. Length: 2.5-3 mm. Differing conspicuously from the preceding forms of acervorum in sculpture and pilosity. The surface of the head, thorax, petiole and 514 WHEELER. postpetiole is distinctly though feebly shining owing to the more superficial punctuation. The rugae on the head and thorax are much more distinct, coarser and further apart. The blunt, erect hairs on the upper surface of the body, especially on the head, thorax and pedicel are much longer, coarser and glistening white. The hairs on the legs seem also to be somewhat coarser than in the various forms of canadensis. The spines of the epinotum are scarcely more than half as long as their distance apart at the base, acute and rather slender. The antennal scapes reach about half way between the eyes and the posterior corners of the head and the basal funicular joints are dis- tinctly shorter and more transverse than in canadensis and its varie- ties. Color dark brown or castaneous, head and sometimes the gaster darker and more blackish; mandibles, antennae and legs pale brown; middle portions of femora, but not the antennal clubs, infuscated. Female. Length: 3.5 mm. Very similar to the worker, the rugosity of the head and thoracic dorsum and the pilosity of the head and thorax even a little coarser and more conspicuous. Body uniformly castaneous, except the pale incisures of the gaster. Wings grayish hyaline, veins pale brown, pterostigma dark brown. Male. Length 3-3.5 mm. Much smaller than the male of canadensis and acervorum. Dark brown; head black, mandibles and legs pale brown, tarsi paler. Wings white, with pale brown veins and stigma. Sculpture of head and thoracic dorsum distinctly more superficial than in canadensis var. yankee and caldcroni, the head, especially, more shining. Pilos- it}^ not more abundant, but paler. Described from numerous specimens of all three phases taken from small colonies under stones in several localities (Manitou, Cheyenne Creek, Red Rock Canyon, Williams Canyon) near Colorado Springs during July and August, 1903. This form is so distinct that it might be regarded as an independent species, but as it has the shape of acer- vorum and the median impression of the clypeus I prefer for the present to regard it as a subspecies. 52. Leytothorax {Mychothora.x) emersoni Wheeler subsp. glacialis Wheeler. Colorado: Florissant 8500 ft. (Wheeler). As I have shown (Bull. Wis. Nat. Hist. Soc. 5, 1907, p. 78 et seq.), this subspecies lives in the colonies of Mynnica brevinodis var. sub- alpina in much the same manner as the typical emersoni of New Eng- land and Canada lives with M. brevinodis var. canadensis. MOUNTAIN ANTS OF NORTH AMERICA. 515 53. Leptothorax {M ychotkorax) emersoni subsp. hirtipilis suhsp. nov. W^orker. Length 2.5 mm. Differing from the typical emersoni and the preceding subspecies in the following characters: the mesoepinotal constriction is more pro- nounced, the pro- and mesonotum being somewhat more con\'ex and at a higher level than the base of the epinotum. The sculpture is much coarser, the rugae on the head being very sharply defined even on the occiput and posterior corners; on the thoracic dorsum the rugae are vaguely longitudinal. The head, thorax and petiole are decidedly opaque. The pilosity is much coarser and more abundant, especially on the thorax and legs. The color is a little darker than that of emersoni and glacialis, with only the anterior border of the gaster yellowish. A single specimen taken from a nest of Myrmiea brevinodis var. snhaJpina on the southern slope of Tunnel Mt., at Banff, Alberta. This shows that the habits are symbiotic as in the other forms of the species. 54. Leptothorax (Mychothorax) hirticornis Emery subsp. formidolo- sus \Yheeler. Colorado: Flagstaff Mt., Boulder Co. (T. D. A. Cockerell). South Dakota: Hill City (Pergande Coll. Nat. Mus.). 55. Aphaenogaster suhterranea Latr. subsp. occidentalis Emery. Washington: Pullman, type locality (Pergande); Pullman and Wawawai (W. M. Mann) ; Almota (A. L. Melander) ; Olympia (T. Kincaid) . Oregon: Ashland (W. Taverner). California: Pacific Grove, Mt. Tamalpais, Yosemite and Lake Tahoe (Wheeler) ; Palo Alto and King's River Canyon (H. Heath) ; Corte Madera Creek, Santa Cruz Mts. (W. M. Mann); Mountain View. Idaho: Moscow (J. M. Aldrich). Utah: East Mill Creek, Salt Lake Co. (R. V. Chamberlin). Colorado: Cheyenne Canyon near Colorado Springs and Boulder (Wheeler). Montana: Helena (W. M. Mann). British Columbia: Dog Lake, Penticton (C. G. Hewitt). This subspecies is extremely common in both the Coast Range and the Sierras of California from sea-level to an elevation of 6000 ft. It appears to be equally common in Oregon and Washington but is much more sporadic in the other localities cited. 516 WHEELER. 56. Aphaenogaster subterranea subsp. valida Wheeler. Recently described from Cheyenne Canyon, near Colorado Springs. 57. Aphaenogaster subterranea subsp. valida var. manni var. nov. Worker. Length 4-5 mm. Differing from the typical valida in color, the body and antennae being yellowish brown throughout, the mandibles, clypeus, and legs paler and clearer yellow. The sculpture of the epinotum and meso- pleurffi and sides of the pronotum much feebler and the upper surface of the pronotum more shining. Numerous workers from Pullman, Washington, (W. M. Mann). Other workers from the same locality but from different nests have the head and gaster darker than the thorax and thus represent transi- tions to the typical valida. 58. Aphaenogaster subterranea subsp. borealis Wheeler. Recently described from worker specimens taken by Prof. J. C. Bradley at Lardo, Kootenay Lake, British Columbia. A number of workers taken by Dr. C. G. Hewitt at Arrowhead Lake, British Columbia, though slightly darker, are also referable to this subspecies. 59. Aphaenogaster patruelis Forel. Known only from the Island of Guadeloupe off the coast of Lower California. 60. Aphaenogaster patruelis var. bakeri Wheeler. This variety was taken several years ago on Catalina Island off the coast of Southern California by Prof. C. F. Baker. 61. Aphaenogaster patruelis var. carbonaria Pergande. According to Forel, this form, originally described as a species, is merely a somewhat darker and more coarsely sculptured variety of patruelis. The types were taken by Eisen at Sierra Laguna and El Chinche in Lower California. 62. Aphaenogaster mutica Pergande. Known from Lower California, Northern Mexico and Western Texas. 63. Aphaenogaster texana Emery. Recorded from Texas, Arizona and Kansas. MOUNTAIN ANTS OF NORTH AMERICA. 517 64. Aphaenogaster texana xnv. furvcscens Wheeler. Described from the Huachuca Mts., Arizona. 65. Aphaenogaster fidva Roger subsp. aquia Buckley var. rudis Emery. Several workers, a dealated female and a male of this form were taken by me at Boulder, Colo. July 29, 1906. Like other forms of the species it is common in the Central and Eastern States and reaches the western limit of its range on the eastern slopes of the Rocky Mts. 66. Aphaenogaster fulva subsp. aquia var. azteca Emery. A form closely related to the preceding but more coarsely sculptured. It was described from Mexico without more precise locality. 67. Aphaenogaster uinta sp. nov. Worker. Length 4.5-5 mm. Head subrectangular, a little longer than broad, as broad in front as behind, with straight sides and rounded posterior corners and with a distinct pit-like impression in the median line on the vertex between the eyes. These are rather large, convex and situated near the median transverse diameter of the head. Mandibles with straight external ■ borders and convex tips, with three larger apical and several more indistinct basal teeth. Clypeus moderately convex, its anterior border rather deeply notched in the middle. Frontal area distinct; frontal carinae small, erect in front, continued behind into slightly converging ridges. Antennae slender; scapes surpassing the posterior border of the head by somewhat less than \ their length, curved at the base and slightly thickened at the apex; funiculi with a distinct 4-jointed club; first funicular joint longer than second; joints 2-7 subequal, nearly twice as long as broad, joints 8-10 subequal, less than twice as long as broad, terminal joint distinctly longer. Thorax slender; pro- and mesonotum together forming a convex, hemispheri- cal mass, the anterior border of the mesonotum not projecting above the pronotum, sloping and concave behind. Seen from above the mesonotum is narrow, more than twice as long as broad. Mesoepino- tal constriction rather deep. Epinotuni long, somewhat less than twice as long as high, in profile with the base perfectly straight and horizontal, and on each side passing into the declivity, with a rectangu- lar projection, representing the spine of other species. Seen from above the dorsal surface of the base is longitudinally impressed in the middle. Petiole short, its peduncle shorter than the node, which is 518 WHEELER. nearly as high as the length of the segment, conical in profile, with strongly concave anterior and abrupt and feebly convex posterior slope. Seen from above the petiole through the node is about one half as broad as its length. Postpetiole shaped like the petiolar node in profile but somewhat lower, from above a little longer than broad and a little broader than the petiole. Gaster rather large, broadly elliptical. Legs moderately slender; spurs distinct on the median and hind tibiae. Shining; mandibles densely striated, clypeus and antennal scapes finely longitudinally rugulose. Anterior portion of head to a short distance behind the eyes finely punctate and feebly longitudinally rugose. Posterior portion of head more shining, more sparsely and more superficially punctate. Pro- and mesonotum above smooth and shining, feebly shagreened; pleurae and epinotum punctate-rugulose and subopaque, the rugules on the base of the epinotum very fine, transverse. Petiole and postpetiole finely shagreened, feebly shining. Gaster very smooth and shining, superficially but distinctly shagreened, with sparse piligerous punctures. Legs moderately shining, finely shagreened. Hairs yellowish; coarse, sparse and erect on the body, very short and subappressed on the antennal scapes and legs. Yellowish red; legs more yellowish; gaster black or very dark brown, posterior borders of segments and anal region testaceous. Female. Length about 7 mm. Head scarcely longer than broad, distinctly broader behind than in front, with more rounded posterior corners than in the worker. Thorax through the wing-insertions as broad as the head through the eyes. Epinotum with two strong, acute spines, which are as long as broad at their bases. In profile the declivity is concave and distinctly shorter than the nearly straight, sloping base. Both the petiole and postpetiole, with their nodes, more compressed anteroposteriorly than in the worker. Wings rather long (8 mm.). In sculpture, pilosity and color resembling the worker, but the head more opaque and more rugose behind. Pronotum transversely rugu- lose, mesonotum and scutellum and portions of mesopleurae smooth and shining; epinotum subopaque, its base transversely, its sides longitudinally rugulose. IMesonotum with three elongate brown blotches. Wings grayish hyaline, with pale brown veins and con- spicuous dark brown stigma. Male. Length nearly 4 mm. Head a little longer than broad, flattened, rounded behind, with MOUNTAIN ANTS OF NORTH AMERICA. 519 straight, marginate occipital border, large eyes and ocelli and very short cheeks. Mandibles small, with 5 or 6 teeth. Clypeus convex, its border straight and entire in the middle. Antennae slender, scapes as long as the first and second funicular joints together; joints of club strongly constricted at their proximal ends so that this portion of the antennae is moniliform. Mesonotum convex, distinctly longer than broad; scutellum as long as broad; base of epinotum straight in profile, gradually sloping to the posterior swellings which are feebly developed, rounded above and angulate behind, but not pointed. Nodes of petiole and postpetiole low and rounded. Legs slender. Mandibles subopaque, very finel,y and indistinctly striate; clypeus smooth and shining; head subopaque, obscurely punctate-rugulose. Remainder of body smooth and shining, except the posterior swellings of the epinotum, which are subopaque and irregularly rugose. Pilosity much as in the worker, but the long, erect hairs on the gaster finer. Piceous; clypeus and legs pale brown; head black; mandibles and antennae sordid yellow. Wings as in the female, but a little more whitish. Described from seventeen workers, one female and one male taken by Dr. R. V. Chamberlin at East Mill Creek, Salt Lake County, Utah. This form is evidently quite distinct from any of our other North American species of Aphaenogaster though most closely related to subterranea. The worker and female of ui7ita can be distinguished from the various forms of this species by their color, the greater length of the scapes and funicular joints and the much larger eyes, the worker by its more rectangular head, peculiar epinotum, more conical post- petiole and larger gaster, the female by its smaller head, shorter epino- tal spines and much darker pterostigma, the male by the very different epinotum, longer mesonotum, more shining and much less densely sculptured head and the paler body and appendages. 68. Stenamma nearcticum Mayr. This species is known only from male and female specimens. What Mayr took to be the worker belongs to brevicorne. The types were from California. My collection contains a male and female from Corvallis, Oregon. 69. Stenamma brevicorne Mayr subsp. diecki Emery. British Columbia: Yale, type locality (G. Dieck). Illinois: Rockford (Wheeler). 520 WHEELER. Pennsj'lvania: Beatty (P. J. Schmitt). Connecticut: Colebrook (Wheeler). 70. Stenamma hrevicorne subsp. heathi Wheeler. California: King's River Canyon (H. Heath). Easily recognized by its uniform light red color and coarse sculpture. 71. Stenamma hrevicorne subsp. sequoiarum subsp. nov. Worker. Length 3-3.3 mm. Resembling the subsp. heathi but larger and of the same color as diecki, with even coarser sculpture than the former, the rugae on the head being stronger and those on the pronotum very coarse and sparse, more longitudinal and less reticulate. The postpetiole is evenly and sharply longitudinally rugose and the rugae at the extreme base of the gaster are very distinct. The base of the epinotum is coarsely and vermiculately rugose. Head broader and the postpetiole distinctly longer than broad, its node lower and less convex than in diecki and heathi. The basal funicular joints are broader and slightly longer than in the other subspecies of hrevicorne. Hairs on the bod.y less abundant and more appressed, especially on the gaster and tibiae. Surface of the head, thorax and pedicel distinctly shining as in heathi and somewhat more opaque than in diecki. Female (dealated). Length 3.6 mm. Resembling the worker; larger than the female diecki, with more robust thorax and the whole body paler and more reddish. The sculp- ture is coarser, the upper surface of the mesonotum and scutellum more sharply longitudinally rugose. Funicular joints longer, hairs on the legs more appressed. Described from a single female and numerous workers taken from several colonies nesting under stones among the large red-wood trees in Muir Woods on Mt. Tamalpais, Cala. A series of workers taken by Prof. H. Heath several years ago at Pacific Grove, Cala. appear to connect this subspecies with diecki. They are somewhat smaller than the specimens of sequoiarum and have a more convex postpetiole, which is longitudinally striate only on the sides and smooth and shining above. The head is somewhat more elongate and the basal funicular joints narrower and shorter. Both these specimens and those of sequoiarum may represent the unknown workers of S. nearcticuvi. 72. Stenamma manni Wheeler. Known only from worker and female specimens taken by Dr. W. M. Mann at Chico in Hidalgo, Mexico. MOUNTAIN ANTS OF NORTH AMERICA. 521 DOLICHODERINAE. 73. Liometopuvi apiculatum Mayr. Mexico: Volcan de Colima, 7500 ft. (C. H. T. Townsend); Pines Altos, Chihuahua and Ciudad de Durango, 8100 ft. (cited in Biol. Centr. Amer.); Guerrero Mill, Hidalgo, 9000 ft. (W. M. Mann). Arizona: Huachuca Mts. 5000 ft. (Biedermann). New Mexico : Las Vegas (Wheeler) ; Las Vegas Hot Springs, 6226 ft. and RomeroviUe (T. D. A. Cockerell); High Rolls, 6550 ft., Alamo- gordo, 4320 ft. (G. V. Krockow) and Beulah, 8000 ft. (H. Viereck). Texas: Paisano Pass, 5079 ft. and Fort Davis, 5400 ft. (Wheeler). Colorado: Canyon City, 5329 ft. and Cotopaxi 6371 ft. (P. J. Schmitt); Manitou and Cheyenne Canyon, 7000 ft. (Wheeler). This ant seems always to be associated with live-oaks. Its hab- its, so far as I have been able to observe them, have been described in my paper "The North American Ants of the Genus Liometopura" (Bull. Amer. Mus. Nat. Hist. 21, 1905, pp. 321-333). 74. Liometopum apiculatum subsp. luctuosum Wheeler. Colorado : Cheyenne Canyon, 7000 ft. near Colorado Springs, type locality (Wheeler). Arizona: Grand Canyon 4000-7050 ft. and Prescott, 5320 ft. (^^^leeler). California: Baldy Peak, San Gabriel Mts., 6500 ft. (Brewster, Joos, and Crawford); Tenaya Canyon, Yosemite, 5000 ft. (Wheeler). Though rarer and more sporadic than the typical form of the species and occidentale, this subspecies seems to have a wide range. The few colonies seen in the Yosemite were running on pine trees. This seems to confirm the opinion I advanced in 1905 that luctuosum is definitely associated with conifers. 75. Liovietopum occidentale Emery. Cahfornia: San Jacinto, 1533 ft. (type locality) ; Mariposa 1962 ft. ; Pasadena and Yosemite 4000 ft. and Wawona (Wheeler) ; Baldy Peak, San Gabriel Mts. (Brewster, Joos and Crawford); Claremont (C. F. Baker and Wheeler) ; Coalinga, below 500 ft., Fresno County, Ontario and Alpine (J. C. Bradley). Oregon : C or vallis . I have recently found a few specimens of the hitherto unknown female and male of this ant from San Jacinto, Cala., in the Pergande 522 WHEELER. Collection (U. S. Nat. Mus.). They differ so much from the corre- sponding phases of apicidahnu that occidcnialc can no longer be regarded as a mere variety of the former, but must be elevated to specific rank. Comparison of the female and male of occidentale, however, with those of the European L. microcephahim may show closer affinities with this species, as a variety of which Emery origi- nally described occidentale. The following descriptions are drawn from two females and a male : Female. Length 10-10.5 mm.; wings 11.5 mm. Much smaller than apicidatum and with much shorter wings (length of apiculatum 12-14 mm.; wings 17-18 mm.) and differing also in the following characters: The head, excluding the mandibles, as long as broad; with the scapes not reaching to the posterior corners, the frontal groove very sharp and distinct and extending from the frontal area to the anterior ocellus. Thorax through the wing insertions not broader than the head, the flattened mesonotum distinctly longer than broad. Surface of the body shining, though coarsely shagreened and sparsely punctate. Hairs short and rather numerous, but much shorter and less abundant than in apiculatum. Color ferruginous brown, gaster darker, lower surface of head, thoracic sutures and legs paler and more yellowish. Wings whitish hyaline, not infuscated as in apiculatum, with paler veins and brown stigma and subcostal vein. Male. Length 9 mm.; wings 10 mm. Differing from the male apiculatum in its smaller size, shorter wings and antennae (length of apiculatum 9-11 mm.; wings 14 mm.), with the wings pale like those of the female, the gaster, legs, genitalia and antennae reddish brown and the hairs, especially on the head, thorax and legs conspicuously shorter and less abundant. The volsellae of the genitalia are shorter and their tips slightly crenate along the dorsal border, whereas this border is smooth in apiculatum. L. occidentale is very abundant among live oaks at low altitudes in the Coast Range of California but less common in the Sierras. It seems not to occur on their eastern slopes, judging from my inability to find it in the Lake Tahoe Region. Only a few colonies were seen in the Yosemite; at Wawona it was more abundant. 76. Tapinoma sessile Say. Washington: Almota (A. L. Melander); Orcus Island, San Juan Island, Pullman and Ellensburg (W. M. Mann); Rock Lake. California: San Jose and Palo Alto (H. Heath); Lompoc, Mt. San Jacinto, Harris, Humboldt County and summit of Mt. Wilson (J. C. MOUNTAIN ANTS OF NORTH AMERICA. 523 Bradley); \Yhittier and Azusa (W. Quayle); Yosemite and Lake Tahoe* (Wheeler). Washington: "Throughout the state" (W. M. Mann). Idaho: Market Lake (J. M. Aldrieh). Nevada: King's Canyon, Ormsby Co. (C. F. Baker). Colorado: Ward 9000 ft. (T. D. A. Cockerell); Buena Vista, Salida, Colorado Springs, Florissant and Boulder (Wheeler) ; Eldora, 8600 ft. and Swift Creek, (W. P. Cockerell) ; Creede Co. 8844 ft. (S. J. Hunter); Tolland and Boulder, 5000-10500 ft. (W. W. Robbins). New Mexico: Las Vegas (Wheeler); Harvey's Ranch, Las Vegas Range, 10,000 ft. (Ruth Raynolds); Manzanares (Mary Cooper); Pecos and Albuquercjue (T. D. A. Cockerell). Arizona: Grand Canyon (Wheeler); Huachuca Mts., 5000 ft. (Biedermann and Wheeler). Texas: Jefferson (E. S. Tucker). Montana: Flathead Lake (C. C. Adams). British Columbia: Golden (W. Wenman); Emerald Lake (W^heeler). Alberta: Banff (Wheeler). This ant is equally abundant and widely distributed in the whole region between the area covered by this list of localities and the Atlan- tic sea-board. It is an essentially eurythermal species, always nesting under stones, logs or bits of wood in open places. The large number of specimens which I have accumulated show considerable variations in size and coloration and some minor structural differences, so that one or more subspecies or varieties may have to be recognized when the material is more closely studied. Camponotinae. 77. Prenolepis imparis Say. California: Piedmont, Alameda County and Berkeley (J. C. Brad- ley); Point Loma, near San Diego (P. Leonard); Palo Alto and San Jose (H. Heath); Santa Inez Mts. near Santa Barbara, Pasadena, San Diego, Claremont, San Gabriel Mts. and Yosemite Village (Wheeler). Nevada: Ormsby County (C. F. Baker). Oregon: Ashland (W. Taverner). Arizona: Grand Canyon, .3670 ft. (Wheeler); Ramsay Canyon, Huachuca Mts. (W. M. Mann). Colorado: Cheyenne Mt. near Colorado Springs (Wheeler). 524 WHEELER. Mexico: CoHma, 7500 ft. (C. H. T. Townsend). This species is also very common throughout North America east of the Mississippi River from Southern Ontario to St. Augustine, Florida, where it was taken by Prof. C. T. Brues. It belongs properly to the transition zone and is, according to my observations, always associated with oak trees. In the Eastern States the var. testacea Emery descends into the Upper and Lower Austral. It is one of the most abundant ants in the sandy pine-barrens of New Jersey and at low altitudes in the mountains of North Carolina. As Emery has shown, the European nitem Mayr is merely a subspecies of imparls with darker wings in the male and female (Deutsch. Ent. Zeitschr. 1910). This author has called attention to the remarkable distribution of the species, the subsp. nitens, the only known Old World form, being confined to Carinthia, Styria, the Balkan Peninsula, Asia Minor and the eastern shores of the Black Sea, whereas the typical form of the species has a very wide range in North America. 78. Lasius niger L. var. sitkaensis Pergande. Alaska: Sitka, type locality (T. Kincaid). British Columbia: Glacier (Wheeler); Dowie Creek and Rogers Pass, Selkirk Mts. (J. C. Bradley). Manitoba: Aweme (N. Criddle); Treesbank (C. G. Hewitt). Ontario: Kenora (J. C. Bradley). Washington: Olympia (T. Kincaid); Seattle (Wheeler); Pullman (W. M. Mann). Oregon: Corvallis. Idaho: Troy (W. M. Mann) ; Moscow (J. M. Aldrich). Montana: Yellow Bay, Flathead Lake (C. C. Adams). South Dakota: Elk Point (E. N. Ainslie). California: Giant Forest, 6500 ft. (J. C. Bradley); Lake Tahoe, 6000-7000 ft. and Camp Curry and Glacier Point, 4000-8000 ft. Yosemite (Wheeler); King's River Canyon (H. Heath). Colorado: Florissant, 8200 ft., Cheyenne Canyon and Williams Canyon, 8000 ft. (Wheeler); Denver (E. S. Tucker); Platte Canyon, 10,000 ft. and Rico, 10,000 ft. (E. J. Oslar). Nova Scotia: Port Maitland (W. Reiff). Maine: South Harpswell (Wheeler); Reed's Island, Penobscot Bay (A. C. Burrill). As shown by the list of localities, this form is very widely distributed through the Canadian zone. The worker and female are larger than any of our other North American forms of L. niger (3.5-4 mm. and MOUNTAIN ANTS OF NORTH AMERICA. 525 8-9 mm. respectively) and quite as large as those of the typical Eurasian form of the species. The worker has the same abundant pubescence and erect hairs on the legs and scapes, but in the female the hairs are less abundant. The ocelli of the worker are very distinct. The body is yellowish brown, with the upper surface of the head, thorax and gaster darker and the appendages a little paler. The wings of the female measure 10-10.5 mm. and are uniformly pale yellowish brown, whereas those of the typical niger are colorless. The male sitkaensis is scarcely smaller than the male niger dark brown and with the wings faintly tinged with the same color. This form passes by gradations into the smaller and darker variety, neoniger Emery and also approaches the true niger and the subspecies alienus. Thus the workers of some of the colonies found at Lake Tahoe and in the Yosemite are much like the European niger, whereas others are smaller and, except for their pilosity, might be confounded with large forms of alicnvs or its variety americanus Emery. 79. Lasiiis niger var. neoniger Emer;^'. Alberta: Banff (Wheeler). California: Lake Tahoe (Wheeler). South Dakota: Elk Point (C. N. Ainslie). Colorado: Broadmoor, near Colorado Springs, Florissant and Salida (Wlieeler); Ward, 9000 ft. and Steamboat Springs (T. D. A. Cockerell). New Mexico: Viveash Ranch, 9000 ft. (Cockerell). Washington: Pullman (W. M. Mann and R. W. Doane); Union City (J. C. Bradley). This variety is also common in cool woods or at higher altitudes throughout the maritime provinces of Canada and the Eastern and Central States as far south as the Black Mts. of North Carolina. The worker and male measures only 2-2.5 mm., the female 6-7 mm. The wings of the female measure 8-9 mm. and both in this sex and the male are clear and hyaline. The body of the worker and female is dark brown or black and the erect hairs on the dorsal surface and on the legs and scapes are abundant and conspicuous. 80. Lasius niger subsp. alienus Forster var. americanus Emery. Alberta: Banff (.J. C. Bradley). British Columbia: Glacier, Field and Emerald Lake (Wheeler); Carbonate (J. C. Bradley). Colorado: Denver (E. Bethel); Silverton, 10,000 ft. (E. T. Oslar); 526 WHEELER. Manitou and Salida (Wheeler) ; Boulder (T. D. A. Cockerell); Canvon City (P. J. Schmitt). Idaho: JuHetta (J. M. Aldrich); Troy (W. M. Mann). Utah: East Mill Creek, Salt Lake Co. (R. V. Chamberlin). New Mexico: Gallinas Canyon (T. D. A, Cockerell); Las Valles (Mary Cooper). Arizona: Grand Canyon, 7000 ft. (Wheeler). California: Glacier Point, 8000 ft., Yosemite (Wheeler). Very common throughout the Middle and Eastern States as far south as Georgia. That this variety should be attached to the European subsp. alienus and not to the typical niger is evident from the absence of erect hairs on the legs and antennal scapes and the sparse pilosity of the body, and also from the fact that the female, especially in the mountains of the western states, is indistinguishable in stature from the female of the true alienus, measuring nearly 8 mm., with wings 9-10 mm. long, although the females of the typical eastern americanus are often not more than 5-5.5 mm., with wings not exceeding 8 mm. Both forms may occur in some of the middle-western states, e. g. in Illinois and Wisconsin. The western form might be distinguished as a variety, for which the name alicno-aincricanus would be appropriate. The males, too, vary greatly in size and the differences of color among the workers of different colonies are considerable. In the Eastern States the workers of a form always found in dry sandy fields are very pale, almost drab-colored, whereas in adjacent woodlands the workers are always darker, varying from dark brown to black. Future study on the basis of a large amount of material will probably lead to the distinction of a number of forms of L. 7iiger in North America, where the species is more variable than it is in Europe. 8L Las'ius {Formicina) hrevicornis Emery. Montana: Elkhorn (W. M. Mann). Colorado: Cheyenne, Canyon, near Colorado Springs (Wheeler). New Mexico: San Geronimo (Mary Cooper). This species, which is very common under stones on dry sunny hill slopes in New England and New York, is rare in the Western States. The worker specimens from Colorado and New Mexico approach those of the following subspecies in the shape of the petiolar node and in having slightly smaller eyes than the typical form, but the differences are not sufficient to justify a new varietal name. 82. Lasius {Formicina) hrevicornis subsp. microps subsp. no v. Worker. Differing from the typical hrevicornis in the much smaller MOUNTAIN ANTS OF NORTH AMERICA. 527 and more nearly eireular eyes wliieli have only 11-13 ommatidia. The funicular joints of the antennae are slightly longer. The petiole is narrower, with straight sides and broadly and feebly emarginate superior border, whereas the typical hrnncornis has the node entire with more rounded sides and border. The pubescence on the head and thorax is distinctly shorter so that the surface is more shining and the color of the body is not a pure but a more brownish yellow. Described from numerous specimens taken from a large colony under a stone at Yosemite Village, 4000 ft., Cala. S3. Lasius (Formiciua) flavus Fabr. subsp. vearcticus Wheeler. Colorado: Topaz Butte, 9000 ft., near Florissant, and Salida (Wheeler). This form is common throughout the Eastern and Middle States but evidently rare in the arid west, probably because of its preference for damp, shady situations. In the eastern .states and Canada I have found it only in moist woods. 84. Lasius (Formicina) flavus subsp. claripennis subsp. nov. Worker. Length 2.6-3 mm. Similar to the typical flavus of Europe and the subsp. ncarcticus but averaging smaller and with the antennae shorter, the scapes scarcely surpassing the posterior corners of the head. The color of the body is brownish yellow as in the true flavus and not pale yellow with whitish gaster as in nearcticus. The eyes are distinctly smaller and much as in the European subsp. myops Forel. Female. Length 7 mm. Differing from the female flavus and nearcticus in the shorter antennae, the scapes of which reach only to the posterior corners of the head. The wings are not infuscated at the base as in these forms, but clear and hyaline throughout and the posterior portion of the head and thoracic dorsum is dark brown, much darker than in nearcticus and perceptibly darker than in the typical flavus. Male. Length 3 mm. Differing from the male flavus and nearcticus in having slightly shorter antennae, in its smaller size and the darker, nearly black color of the body. Described from numerous workers, four females and six males taken Aug. 20th from several colonies nesting under stones on the southern slope of 't'unnel Mt. at Banff, Alberta. Several workers received from P'arewell Creek, Southern Saskatchewan (E. G. Titus), three workers from Pullman, Washington, and a series of workers, males 528 WHEELER. and females from Creede Co., Colo., 8844 ft. (S. J. Hunter) also belong to this subspecies. It is evidently quite distinct from the other forms o1 flavus. It resembles the subspecies myops in preferring hot, stone-covered slopes to moist, shady places as a habitat. 85. Lasius {Formicina) umhratus Nyl. subsp. subumbratus Viereck. New Mexico: Beulah, 8000 ft., type-locality (T. D. A. Cockerel!). Colorado: Cheyenne Canyon near Colorado Springs, Williams Canyon near Manitou, and Boulder (Wheeler); Canyon City (P. J. Schmitt). Utah: Little Willow Canyon, Salt Lake County (R. V. Chamberlin). Arizona: Wilhams, 7000 ft. (Wheeler). California: Angora Peak, near Lake Tahoe, 8000 ft. (Wheeler). Ontario: Ottawa (Wheeler). Quebec: Hull (Wheeler). Maine: Reed's Island, Penobscot Bay (A. C. Burrill). Nova Scotia: Digby (J. Russell); Bedford (W. Reiff). The list of localities shows that this form has a very wide range. It is the most boreal of our forms of umhratus and is confined to the Canadian Zone. 86. Lasius (Formicina) umhratus subsp. mixtus Nyl. var. aphidicola Walsh. This form, so abundant in many localities east of the Rocky Mts., is very rare further west. During the summers of 1903 and 1906 I found a few colonies near Florissant and Colorado Springs, Colorado. They nest by preference in moderately moist, shady places. This probably accounts for their almost complete absence from the arid portions of the country. 87. Lasius (Formicina) umhratus subsp. vcstitus W^heeler. Known only from a female specimen taken by Prof. J. M. Aldrich at Moscow, Idaho. 88. Lasius (Formicina) humilis sp. nov. Worker. Length 1.5-1.7 mm. Head as broad as long, a little narrower in front than behind, with broadly and feebly excavated posterior border and feebly and regularly convex sides. Eyes very small, somewhat larger than in the typical brevicornis, flat, with only about six ommatidia in their greatest diam- eter. Antennae slender; scapes extending beyond the posterior MOUNTAIN ANTS OF NORTH AMERICA. 529 corners of the head, funicuH scarcely enlarged at their tips; joints 2-3 as broad as long, all the other joints distinctly longer than broad, the ninth and tenth being nearly 1^ times as long as broad. Clypeus very bluntly subcarinate. Frontal area large, triangular. Palpi rather long, the six joints of the maxillary pair gradually decreasing in length towards the tip as in other members of the subgenus. Thorax rather short, the pro- and mesonotum together as long as the epino- tum; mesonotum as long as broad, the promesonotal suture not deeply impressed; mesoepinotal constriction short but moderately deep; epinotum in profile with the convex base about j as long as the flat, sloping declivity. Petiole narrow and rather high, much compressed anteroposteriorly, with flat anterior and posterior surfaces, straight, nearly subparallel sides and rather sharp, entire and evenly rounded superior border. Gaster broad, flattened dorsoventrally. Surface shining; mandibles finely striated; remainder of body very finely and superficially shagreened. Pubescence and hairs pale yellow, the former appressed, abundant and moderately long on the body and appendages, the latter blunt and erect, very sparse on the head, more numerous on the thoracic dorsum and still more abundant on the gaster. Pale yellow; head and antennae a little darker; mandibles with reddish borders and teeth. Female. Length 3.5 mm. Head subrectangular, slightly broader than long, with rather deeply and broadly excised posterior border and straight cheeks. Eyes large, convex, more than half as long as the cheeks. Antennal scapes sur- passing the posterior corners of the head by about | their length; all the funicular joints distinctly longer than broad. Thorax not broader through the wing-insertions than the head through the eyes, flattened above; mesonotum nearly as long as broad. Petiole with more convex sides and blunter superior border than in the worker, this border feebly eraarginate in the middle in some specimens. Wings rather long. Sculpture and pubescence much as in the worker, erect hairs on the thorax and gaster apparently less numerous and conspicuous. Color like that of the worker, but the occipital portion of the head, the pro- and mesonotum, scutellum and dorsal surface of the gaster pale brown. Wings grayish, not infuscated at their bases, with pale brown veins and stigma. Described from nine workers and three females taken by Dr. W. M. Mann at Pyramid Lake, Nevada. 530 WHEELER. This ant might be regarded as an extreme subspecies of umbratus, but the worker and female are decidedly smaller even than the corre- sponding phases of the eastern subsp. minutus Emery, the female, indeed, being smaller than that of any other North American Lasius. The different proportions of the funicular joints seem to justify a specific name, as the joints 9 and 10 are very distinctly longer. The eyes of the worker are smaller, the promesonotal suture is much less deeply impressed and the mesonotum much less convex and projecting, the mesoepinotal impression shallower than in umbratus and the petio- lar border not so sharp. 89. Lasius (Acanthomyops) occidentalis Wheeler. Colorado: Colorado Springs and Ute Pass (Wheeler). New Mexico: Pecos and Trout Spring, Gallinas Canyon (T. D. A. Cockerell); Manzanares (Mary Cooper); Albuquerque (W. H. Long). This small species is not known to occur east of the Rocky Mts. and appears to have the most limited range of any species of the sub- genus. 90. Lasius {AcantJwmyops) murphyi Forel. North Carolina: Morganton, type locality (Forel). New York: Cold Spring Harbor, L. I. and Bronxville (Wheeler). Ontario : Toronto. Colorado: Boulder (P. J. Schmitt and T. D. A. Cockerell). Montana: Helena (W. M. Mann). This ant appears to belong to the warmer and dryer portions of the Transition Zone and to be rare in all parts of its range. It forms large colonies under stones in open woods. 91. Lasius (Acanthomyops) latipes Walsh. California: Mt. Tamalpais (C. G. Hewitt); Mountain View. Washington: Pullman and Wawawai (W. M. Mann); Almota (A. L. Melander); Rock Lake. Idaho: Julietta (J. M. Aldrich). Utah: Salt Lake Co. (R. V. Chamberlin). Colorado: Manitou and Florissant (Wheeler); Boulder (P. J. Schmitt and T. D. A. Cockerell). New Mexico: Las Vegas (T. D. A. Cockerell); Albuquerque (W. H. Long). Illinois: Rockford (Wheeler). Pennsylvania: Enola. MOUNTAIN ANTS OF NORTH AMERICA. 531 New Jersey: Weasel Mt. and Lakehurst (Wheeler). New York: Bronxville and White Plains (Wheeler). Connecticut: Colebrook (Wheeler). Massachusetts: Franklin and Boston (Wheeler); Needham (A. P. Morse). As shown by the list of localities, this species has a very wide range, from Boston to San Francisco. It is rather sporadic and nests under large stones in dry fields and pastures. 92. Last us {Acanthomyops) inter jecius Mayr. Washington: Pullman (W. M. Mann). Colorado: Manitou, Cheyenne Canyon and Colorado Springs (Wheeler); Longmont (P. J. Schmitt). New Mexico: Las Valles (Mary Cooper). Montana: Flathead Lake (C. C. Adams). Specimens of all three phases from these localities are indistinguish- able from those of the Central and Eastern States where the species is much more common. It nests in rather dry, sunny places. The basal border of the mandibles in the worker and female, is distinctly denticu- late, a peculiarity which I have not observed in our other species of the subgenus Acanthomyops. 93. Lasius {Acanthomyops) interjectus subsp. californicus subsp. nov. JVorker. Length 2.6-3 ram. Much smaller than the worker of the typical form, which measures 4-5 mm., with the basal border of the mandibles very indistinctly denticulate and the funicular joints of the antennae a little shorter and the scapes much shorter, extending only slightly beyond the posterior corners of the head. The sides of the head are distinctly less convex. The mesoepinotal constriction is much feebler and the base of the epinotum much less convex, narrower and rounded. Color, sculpture and pilosity much as in the typical form. Female. Length 7.5 mm. Somewhat smaller than the typical form and of a different color, the thorax, petiole and gaster being rich reddish castaneous, the head, base of first gastric segment and the appendages red. The infuscation of the bases of the wings is scarcely perceptible. The petiole is much broader and more deeply excised than in the female of the typical interjectus and the funicular joints of the antennae are distinctly shorter. Described from eleven workers taken by myself from a single colony 532 WHEELER. in Palmer's Canyon, San Gabriel Mts., near Clareraont, Cala., at an altitude of about 2000 ft., and a single female from the same moun- tains (F. Grinnell). 94. Lasius (Acanthomyops) interjectus subsp. coloradensis subsp. nov. Worker. Very similar to the preceding subspecies and of the same size but with distinctly larger eyes and finer and conspicuously more abundant erect hairs on the head, thorax and especially on the gaster. The proportions of the scape and funicular joints and the shape of the thorax and petiole are the same as in californicus. Female. Length 4.5-5 mm. Decidedly smaller than the female of californicus, with the head as well as the thorax deep castaneous. Mandibles, antennae and legs brownish yellow, the femora somewhat infuscated in the middle. Wings grayish hyaline, not darker at the base, the veins and stigma pale. Petiole less deeply emarginate above and much narrower than in californicus. Erect hairs on body more abundant. Male. Length 3 mm. Much smaller and more pilose than the male of the typical inter- jectus, with uniformly grayish, hyaline wings. The superior petiolar border is noticeably blunter and the funicular joints are distinctly shorter. Described from a dozen workers and as many females taken by myself at Manitou, Colo, (type locality), Aug. 9, 1903, six workers, seven females and two males taken by Mr. E. Bethel at Denver, a single dealated female taken by Prof. Cockerell at Las Vegas, New Mexico and three workers from Manzanares in the same state (Mary Cooper). 95. Lasius {Acanlhomyoys) interjectus subsp. arizonicus subsp. nov. Worker. Length 3.5-4.5 mm. Larger than californiciis and coloradensis but somewhat smaller than the typical interjectus and of a slightly paler yellow color. The proportions of the antennal scape and funicular joints and the shape of the thorax are much the same as in interjectus, but the petiole is much smaller and narrower. The eyes are considerably larger and more convex. The erect hairs on the head, thorax and gaster are much fewer, there are usually no hairs on the gula, and the pubescence on the body and especially on the gaster is much shorter than in typical interjectus so that the surface appears very glabrous and shining. MOUNTAIN ANTS OF NORTH AMERICA. 533 I took many workers of this species in Miller Canyon, Huachuca Mts., 5000 ft., during November 1910 and received additional material from Mr. Biedermann, who took it in Carr Canyon, and from Dr. W. M. Mann who took it in Ramsay Canyon in the same mountain range. The subspecies is very easily recognized by its larger eyes, peculiar pilosity and very smooth surface. 96. Lasius {AcantJiomyops) interjectus subsp. mexicanus Wheeler. I have recently described this subspecies from specimens of all three phases taken by Dr. Mann at Guerrero Mill in the State of Hidalgo, Mexico, at an altitude of 8500-9000 ft. 97. Lasius {AcantJiomyops) claviger Roger. I have seen only a few specimens of this very common eastern species from the west, a worker taken at Old Pecos Pueblo, New Mexico, by Prof. Cockerell and several workers and females taken by Dr. Mann at Helena, Montana. In Massachusetts and Connecticut claviger is the most abundant Acanthomyops. The small subspecies of inter- jectus described above, show that the species is by no means so distinct from claviger as we had supposed. The small form described by Emery from the Eastern States as claviger var. subglaber should be regarded as a subsjiecies. I have taken all three phases of it at Rock- ford, 111., and on Great Blue Hill, near Boston, Mass., and have seen specimens from the District of Columbia (cotypes from Pergande), Delaware Co., Pa. (Cresson) and Algonquin, 111. (W. A. Nason). At first sight this form closely resembles interjectus subsp. coloradensis in size, but the workers and females of this form are much more pilose, the antennal funiculi are distinctly less clavate and the female is much darker. 98. Formica sanguinea Latr. subsp. suhnuda Emery. British Columbia: Field and Emerald Lake (Wheeler). Alberta: Lake Louise and Banff (Wheeler). California: Fallen Leaf Lake and Glen Alpine Springs, near Lake Tahoe (Wheeler); Sugar Pine, Madera County (J. C. Bradley). Idaho: Troy (W. M. Mann). Washington: Seattle (Wheeler). Colorado: San Juan Mts., 12,000 ft.. Bullion Peak, Park Co., 13,000 ft., and Gibson's Gulch, Hayden Peak, 10,000 ft. (E. J. Oslar); Tol- land (W. W. Robbins). In my "Revision of the Ants of the Genus Formica" I have cited 534 WHEELER. this ant from many other locaHties from British Columbia to Connecti- cut. It is very widely distributed in the Transition and Canadian Zones. Of the numerous colonies seen in California and British Amer- ica during the summer of 1915 few contained slaves (F.fusca). 99. Formica sanquinca subsp. jmbenda Emery. Arizona: Graham Mts. (E. G. Holt). Recorded from various localities in South Dakota, Colorado, Utah, Washington, Montana, New Mexico, Texas, Missouri and Illinois. 100. Formica sanguinea subsp. obtusopilosa Emery. An imperfectly known subspecies described from a single worker taken in New Mexico. 101. Formica munda Wheeler. Known from several localities in Colorado, New Mexico, South Dakota, Montana and Alberta where it occurs below elevations of 7000 ft. 102. Formica munda var. alticola var. nov. Worker. Length 4.5-5 mm. Differing from the typical munda in having the red portions of the body of a much deeper shade, and the petiole and dorsal portion of the head infuscated. The erect hairs on the head and thorax are distinctly more abundant than in munda. Described from seventeen specimens taken by Mr. E. J. Oslar in Jefferson County, Colorado at an altitude of 9500 ft. This is clearly an alpine variety. One of the specimens is a pseudogyne, with very convex pro- and mesonotum and well-developed scutellum and meta- notum, but without traces of wings. 103. Formica emeryi Wheeler. Known only from Broadmoor, near Colorado Springs, Colo. 104. Formica manni Wheeler. Idaho: Boise (A. K. Fisher). Originally described from several localities in Washington and Owen's Lake, California. 105. Formica perjnlosa Wheeler. Occurring at rather low elevations in Colorado, New Mexico, Ari- zona, Western Texas and Northern Mexico. AIOUNTAIN ANTS OF NORTH AMERICA. 535 10(). Formica hradlcyi Wheeler. Colorado: San Miguel, 12,000 ft. and Bullion Peak, Park Co. 12,000 ft. (R. J. Oslar). Montana : Missoula. Previously known only from workers taken at Georgetown, Colo, and Medicine Hat, Alberta. It is evidently an exclusively alpine species. The two specimens from Missoula are females. They measure nearly 7 mm. and are colored like the worker, red throughout, except the posterior borders of the gastric segments which are fuscous. The surface of the body is subopaque. The petiole is cuneate in pro- file, broad below, with flat anterior and posterior and rather sharp, emarginate superior border. The notch in the middle of the anterior clypeal border is very distinct. The wings are grayish hyaline, with brown stigma and yellowish brown veins. 107. Formica rufa L. subsp. obscuripes Forel. British Columbia: Glacier (Wheeler). Alberta: Banff (Wheeler). Manitoba: Treesbank (C. G. Hewitt). Montana: Beaver Creek (S. J. Hunter). Wyoming: Cheyenne (Fanny T. Hartman): Rock River (S. J. Hunter). Colorado: Creede, 8844 ft. (S. J. Hunter); Tolland (W. W. Rob- bins); Jefferson (A. K. Fisher). California: Tallac, Lake Tahoe (W' heeler). Washington: The eastern part of the state (W. M. Mann). The attempts in my "Revision" to dissipate the confusion in regard to our American forms of rufa, prove to have been unsuccessful and I must here make another attempt. I believed that I could recognize four forms of this species, the subsp. obscuripes Forel, the subsp. aggcrans (a new name for Emery's rubiginosa (nom. praeocc.)), the var. melanotica Emery and a var. whympcri described by Forel as belong- ing to obscuripes but at the time unknown to me. I have since found this variety in British Columbia and am able to state that it does not belong to rufa or obscuripes but is a distinct species of the microgyiia group and is very close to the form I described as F. adamsi {vide infra). The var. melanotica is a very definite color \ariety of obscu- ripes and need not be discussed. Doubt remains then only in regard to the typical obscuripes and aggerans. Although I studied much material from a number of localities I was unable to distinguish these forms satisfactorily for the reason that both were inadequately 536 WHEELER. described by Emery and Forel and because the latter published con- flicting descriptions of obscuripes. His original description (C. R. Soc. Ent. Belg. 1886, p. 2) runs as follows: "Ouvriere. Long. 3.8-8 mm. Tres semblable a la F. rufa i. spec. d'Europe. INIais elle est plus petite; les grandes ouvrieres sont d'un rouge plus clair et presque ou entierement sans tache sur la tete et le thorax, tandis que les pattes et I'ecaille sont d'un brun noiratre. Les petites ouvrieres sont beau- coup plus foncees et tachees de brun sur la tete et le thorax. L'abdo- men est mat, noir, et a une pubescence grise un peu plus forte que chez la F. rufa i. spec, tandis que la pilosite est plutot un peu plus faible. — Green River, Wyoming (Scudder)." Recurring to this form in con- nection with his description of whymperi (Ann. Soc. Ent. Belg. 48, 1904, p. 152) Forel says: "Emery rattache V obscuripes comme variete a Vobscuriventris. Mais Vobscuriventris est beaucoup plus poilue et a les tibias garnis de poils dresses, ce qui n'est pas le cas de Vobscuripcs, dont les tibias n'ont qu' une pubescence adjacente et dont le corps n'a que tres peu de poils dresses, beaucoup moins que chez la pratensis d'Europe et meme que chez la rufa typique. Je maintiens done Vobscuripcs comme race ou sous-espece distincte." Finding that there .was considerable variation in the pilosity of my series of rufa from different colonies and localities and relying on these descriptions, I naturally referred the more pilose forms to Emery's rubiginosa and the less pilose forms to Forel's obscuripes. Since the publication of my " Revision" Forel returns to the subject with the fol- lowing statement (Deutsch. Ent. Zeitschr. 1914, p. 619): "Ich habe leider bei Gelegenheit der Beschreibung dieser Rasse (obscuripes) und bei derjenigen der var. whymperi For. die Tatsaohe iibersehen, dass die Originaltypen der obscuripes, die ich noch in Anzahl besitze, nicht, wie ich angegeben hatte, ohne abstehende Haare, son- dern sehr deutlich, obwohl meistens sparlich abstehend behaart sind. Die Behaarung wechselt, wie Wheeler von aggerans angibt, ziemlich stark bei den verschiedenen Individuen und ich hatte bei der Beschrei- bung ein solches angesehen, wo sie fast oder ganz fehlten, ebenfals ist der Hinterleib matt mit feiner rauher Pubescens, so dass ich mit dem besten Willen keinen Unterschied zwischen obscuripes und aggerans finden kann und diese beiden Formennamen als synonym betrachten muss; auch die Haare des Hinterleibs sind gleich. Dagegen bleiben die v. melanotica Em. und whjmperi For. (letztere ohne abstehende Haare) bestehen. — Lake Tahoe, Kalifornien." As I collected many specimens of this ant at Lake Tahoe I am undoubtedly in possession of specimens which Forel now pronounces MOUNTAIN ANTS OF NORTH AMERICA. 537 to be his obscuripes. These also undoubtedly bclon