'T ftOVl.9 1943 Of ILLINOIS ZOOLOGICAL SERIES OF FIELD MUSEUM OF NATURAL HISTORY Volume 24 CHICAGO, OCTOBER 20, 1943 No. 27 SNAKES OF THE PERUVIAN COASTAL REGION BY KARL P. SCHMIDT CHIEF CURATOR, DEPARTMENT OP ZOOLOGY AND WARREN F. WALKER, JR. HARVARD UNIVERSITY The Andes divide Peru into three regions familiar to every Peruvian as the "costa," the "sierra," and the "montana." These regions, the desert coast with its numerous oases formed by the transecting valleys; the sierra with its high plateaus and mountain ridges extending far above snow line; and the tropical forest region of the deep valleys and of the connected Amazonian lowland east of the mountains, are in fact the major phytogeographic and zoogeo- graphic divisions of Peru. The herpetological fauna of the highland is extremely limited, with only a single species of snake, Tachymenis peruviana, traceable above 12,000 feet, together with a common lizard and a few frogs and toads. The tropical lowland has the rich and complex fauna of the Amazon Basin, further complicated by the forms proper to the cloud forest zone at intermediate altitudes on the eastern side of the Andes. In this region much collecting remains to be done before an adequate study can be made even of creatures as relatively conspicuous as the snakes. The snake fauna of the coastal region, though somewhat impoverished in species, is of great interest, since the species and subspecies are with few exceptions endemic. In view of the relative simplicity of the coastal fauna, and with the accumulation of considerable collections from coastal Peru in Field Museum and in the Museum of Comparative Zoology, we feel that a review of the snakes of this faunal region may be a useful preliminary to further studies on the amphibians and reptiles of Peru. In addition to a summary of the literature and an attempt to disentangle the nomenclature of the coastal forms, we here report No. 533 297 I WAT. 298 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. 24 on two considerable collections from the Peruvian coast. The first of these was assembled by Dr. Axel A. Olsson while stationed at Negritos as geologist for the International Petroleum Company, with some increments from Mr. E. W. MacCormack, and more recently from Mrs. Harriet Frizzell, also of Negritos. The second consists of an accumulation of preserved snakes presented to Field Museum's Magellanic Expedition by Sr. Constante Larco Hoyle on the occasion of a visit of the senior author to the Hacienda Chiclin (north of Trujillo) in 1939. A few additional specimens from the coastal region were received from other sources as results of the continued interest of Mr. Colin C. Sanborn, also of the Magellanic Expedition of 1939. Mr. Sanborn collected at Chucurapi, the hacienda of the Romana family near Mollendo, in 1939, and in the little-known lea region in 1942. A single small snake of the genus Leptotyphlops was presented by Mr. Bruce A. Hertig, of Lima, with several other additions to the collection from Dr. Marshall Hertig, of the Institute Nacional de Higiene y Salud Publica, in Lima. The collections of snakes lent to Field Museum for study by the University of Arequipa have been reported upon by the present authors. This collection makes available a considerable number of specimens from the southern portion of the coastal region of Peru. Finally, the junior author has had the advantage of examining all of the Peruvian collection at the Museum of Comparative Zoology, a collection which has been augmented recently by specimens received from Mr. W. F. Walker, Sr., of Oroyo, Peru, and from Messrs. J. A. Griswold, Jr., and G. P. Gardner, obtained on their expeditions to Peru. The coastal region of Peru may be defined for the purpose of the present paper as the coastal drainage extending from the Ecuadorean border to Chile, and from the Pacific coast to the crest of the western cordillera. The Catamayo Valley, extending into the Ecuadorean Department of Loja, the low passes of the Cordillera Occidental in Cajamarca at the north, and the southwestern continuation of the coastal desert into Chile, make necessary some consideration of these outlying areas in the discussion of various species in our list. The Hispanic Map published by the American Geographic Society indicates that there are three passes over the western cordillera near the Ecuadorean border of Peru somewhat below 10,000 feet elevation, and various passes between coastal Piura and Lambayeque and Andean Cajamarca at less than 8,000 feet. These passes apparently explain the presence of some non-endemic . Z.7 FIG. 26. Map of Peru, showing localities mentioned in the text. 299 300 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. 24 forms of Amazonian or Ecuadorean origin in the northern part of the coastal area and also throw light on the transgression of certain elements of the coastal fauna into the arid northern portion of the Maranon Valley. Farther south the passes are at fourteen to sixteen thousand feet, well above the altitude reached by any species of the coastal fauna proper. This stupendous mountain barrier is not again transgressed by reptiles of the lowland east of the Andes until, at the south, the lake region of southern Chile again provides passes at low altitude. The Peruvian coastal region is one of the most barren areas in the world, much of it rock and sand desert, extending for miles without visible plant or animal life. It contrasts strongly with the Sonoran desert in southwestern North America, familiar to North American biologists, with its wealth of conspicuous plants and animals adapted to desert conditions through age-long evolution. Our Sonoran desert is literally the headquarters of the reptilian fauna of a continent, with numerous forms exhibiting remarkable and extreme adjustment to desert conditions. In the Peruvian desert, the reptiles form a mere appendage to the rich reptilian fauna of South America as a whole, and in spite of the endemism of numerous species, it seems clearly to be a recent desert, in which there has not been time for the evolution of specifically xerocole types. The most remarkable botanical feature of coastal Peru, the rich seasonal flora of the "lomas," which depends on concentration of the coastal fogs in certain slopes and in certain valleys, appears to have no associated amphibians or reptiles. There are considerable botanical differences between the Piura region and the coastal desert farther to the south. The most useful account of the phytogeography of Peru appears to be that of Weberbauer (1922, 1936). Much of the interest of the Peruvian coastal fauna and flora lies in its linear extent from north to south; the biota is richest in Piura at the north, becoming gradually impoverished to the south, where the coastal plain is all but pinched out between the mountains and the sea in northern Chile. In this region only a minimum of land life persists. To the south of Antofagasta, a scrub vegetation develops, essentially with only an impoverished desert fauna. The characteristic Peruvian lizard Tropidurus peruvianus persists on the coastal strip and the common highland snake of Peru (Tachy- menis peruviana) descends to low altitudes in central Chile. In southern Chile, where the humid evergreen forest begins, there is a radical faunal change, with numerous endemic genera of frogs, 1943 PERUVIAN SNAKES SCHMIDT AND WALKER 301 though none of snakes. It is evident, even from our necessarily limited studies, that a systematic survey of the coastal fauna through its 2,500-mile range from north to south would disclose numerous variation clines, the establishment of which is necessary to any definitive taxonomic arrangement of the elements compos- ing the fauna. LIST OF LOCALITIES The localities mentioned in the text are shown on the accom- panying map. A list of the coastal localities from which specimens have been examined follows: Arequipa: The vicinity of Arequipa, capital of the Department of Arequipa, elevation 7,500 feet. Arid slopes, a semi-desert except in irrigated valley bottoms. Bayovar: A port on the southern shore of the Bahia de Sechura, Department of Piura. Cajamarquilla: Adobe ruins in the Rimac Valley a few miles inland from Lima, Department of Lima. Matted bromeliad vegetation. Chiclin: A sugar-producing hacienda between Trujillo and Chicama, Depart- ment of Libertad. Irrigated cane fields and pastures, surrounded by sandy desert toward the coast and by stony pavement desert farther inland. Chimbote: A port near the mouth of the Rio Santa at the northern boundary of the Department of Ancash. Chongollapi: A village at the desert border in Piura. Chosica: A resort town above Lima, in the Rimac Valley, at an elevation of 2,800 feet, Department of Lima. Chucurapi: A sugar hacienda near Mollendo, in the Department of Arequipa. lea: A considerable metropolis inland from the port of Pisco, in a broad allu- vial valley. Jequetepeque: A valley in the Department of Libertad, entering the sea near Pacasmayo. Lima: Capital of Peru, Department of Lima, on the irrigated alluvial plain of the Rimac River. Majes Valley: A long, well-watered valley north of the Vitor Valley, Depart- ment of Arequipa. Negritos: A port in northern Piura just south of Talara. Pacasmayo: The port of entry for Cajamarca in the northern part of the Department of Libertad. Quebrada Montero: An arroyo in the oil-field region, Department of Piura. Quebrada Parinas: An arroyo emptying into the ocean at Parinas just south of Negritos, Department of Piura. Quebrada Paxul: An arroyo in the oil-field region, Department of Piura. Quebrada Sal Grande: An arroyo in the oil-field region, Department of Piura. Quebrada Seca: An arroyo in the oil-field region, Department of Piura. 302 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. 24 Surco: A small town at an elevation of about 6,000 feet, in the Rimac Valley below Matucana, Department of Lima. Talara: The port and headquarters of the International Petroleum Company, Department of Piura. Tambo: A small town on the Rio Tambo, in the southern part of the Depart- ment of Arequipa. Toquepala: A mining camp at an elevation of 8,000-10,000 feet, east of the city of Moquegua, Department of Tacna. Vitor Valley: A valley crossing the coastal desert of the Department of Arequipa below Arequipa. Other localities from which specimens have been examined include especially Perico, the Rio Maranon, and Bellavista, in the Maranon Valley (eastern Cajamarca), where the late G. K. Noble made collections for the Museum of Comparative Zoology in 1916. Specimens of coastal species in the collections of the University of Arequipa recorded as from "Selvas de Sandia" and "Madre de Dios" appear to bear erroneous data (Schmidt and Walker, 1943, p. 284). Serpentes Leptotyphlopidae Leptotyphlops rufidorsus Taylor Leptotyphlops rufidorsum Taylor, Univ. Kans. Sci. Bull., 26, p. 533, fig. 2, 1940 Lima, Peru. A medium-sized Leptotyphlops, without cephalic or caudal spots, with a median dorsal brownish band covering three scale rows and the adjacent half scale rows; dorsal scales about 260. Known only from the type locality and from Chiclin, Libertad, as here reported, thus possibly characteristic of the central portion of the desert region. A single specimen, No. 34305, from Chiclin, Libertad, has dorsal scales 256, caudals 16, scales around body 14, around mid-tail 10; length 241, tail 12; diameter of body contained in total length about 40 times. Supraocular and labial separating rostral from ocular on both sides. Coloration in close agreement with Taylor's description. We have read Werner's description of Glauconia albifrons var. rubrolineata (Werner, 1901, p. 6), said to be from Lima, with atten- tion.. It does not appear to refer to any of the species here recorded, and, as remarked below (p. 313), the type locality may well be erroneous. 1943 PERUVIAN SNAKES SCHMIDT AND WALKER 303 Leptotyphlops subcrotillus Klauber Leptotyphlops subcrotilla Klauber, Trans. San Diego Soc. Nat. Hist., 9, pp. 59-66, fig. 2, 1939 Grau Tombes, northern Peru [=Grau, Tumbez]. A small slender worm snake of the albifrons group, with a white spot on the rostral and on the caudal spine; dorsal scales from rostral to tail spine about 330. Known only from the type locality and from Chiclin, Libertad, as here reported, thus apparently ranging through the northern desert region. Two specimens, Nos. 34267 and 34304, from Chiclin, Libertad, agree excellently with Klauber's description. The dorsal scales number respectively 325 and 324; scale rows 14; scales around mid-tail 10; total length and tail length 137 and 6, and 184 and 8; diameter of body contained in total length 70 to 90 times. Leptotyphlops melanurus sp. nov. Type from Chiclin, Libertad, Peru. No. 34269 Field Museum of Natural History. Presented to Magellanic Expedition of Field Museum, November, 1939, by Sr. Constante Larco Hoyle. Diagnosis. A small slender worm snake, nearly uniform in coloration, not distinctly lineate; no caudal spot, rostral spot occasionally present; dorsal scales 395; ocular shield in contact with the nasal. Description of type. Body slender, head very little widened, tail about three times as long as its diameter, ending in a small spine-bearing scale. Snout rounded, projecting. Rostral narrowed posteriorly, extending backward barely to the eye; upper portion of nasal considerably larger than lower; ocular broadly in contact with nasal; ocular widest at eye-level, eye dis- tinct, at anterior border of ocular supraoculars wider than long, posterior larger than anterior, both larger than the median series of scales; third scale of median series largest, followed by a narrower scale with a small scale on each side, while the fifth scale is wider, though not longer, than the third; scales following the fifth gradually narrowed to the uniform mid-dorsal series; parietals about as wide as posterior supraoculars; chin shields small. The scales are in 14 rows throughout the length of the body, 10 around the middle of the tail. Dorsal scales from rostral to caudal spine 395; caudals 18. 304 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. 24 General color brown, a little lighter beneath, the outlines of the scales lighter; a light spot on the rostral, none on the tail; upper head shields all with light pores. Measurements of type. Length 135; tail 6; diameter of body 2. Notes on paratype. The single paratype, No. 34268, obtained with the type at Chiclin, measures only 91 mm., tail 5. It agrees almost exactly with the type, with dorsal scales 396 and caudal 20. Range. Known only from type locality. Leptotyphlops tessellatus Tschudi Typhlops tessellatum Tschudi, Fauna Peruana, Herp., p. 46, 1845 Lima. Two specimens of a small Leptotyphlops of the albifrons type from Lima may be referred with little hesitancy to Tschudi's species. One of these was collected and presented by Mr. Bruce A. Hertig, the other was collected in the wall of an old adobe house in Lima by Mr. Felix Woytkowski, a well-known collector of Peruvian insects. Leptotyphlops tessellatus is here redescribed in some detail for comparison with recent descriptions of species of this genus. Diagnosis. A small worm snake with lineate pattern, darker on the upper half of the body, and with white spot present on rostral and tail spine. Ocular separated from nasal by supraocular and labial; dorsal scales about 260. Description (No. 35097). Body slender, head scarcely wider than body, tail three and one-half times as long as its diameter, ending in a rather large pointed scale. Snout rounded, projecting. Rostral sharply narrowed posteriorly, extending backward barely to the level of the eye; upper and lower portions of nasal subequal; ocular separated from nasal by a contact of the supra- ocular with the first labial; eye distinct at upper anterior corner of the ocular; anterior supraoculars a little smaller than posterior, directed obliquely forward and outward; posterior supraoculars about equal to parietals; median scales very narrow, fifth behind rostral widest. The scales are in 14 rows throughout; 10 scales around middle of tail. Dorsal scales from rostral to tail spine 261; caudals 17. General color brown, lighter on the edges of the scale rows, producing a lineate appearance; seven dorsal rows darker than the seven ventral; a light spot on the rostral and lower portions of the nasals, and one covering the entire tail spine and two adjacent 1943 PERUVIAN SNAKES SCHMIDT AND WALKER 305 scales; upper head shields all with light pores. Length 90; tail 5; diameter of body 2. The second specimen in our collection (No. 36726) measures 102; tail 6; diameter of body 2. It has 262 dorsal scales from rostral to tail spine. Range. Known only from the coastal area of north-central Peru near Lima. Remarks. There appears to be no doubt that the Leptotyphlops albifrons of authors is an omnium gatherum of species of varying degrees of distinctness. In view of the generally endemic nature of the Peruvian coastal fauna, it is extremely unlikely that true albifrons, an Amazonian species, should occur there. It is never- theless surprising that four fully distinct species of Leptotyphlops should occur in this faunal area. The reference of the present form to tessellatus is based primarily on the fact that the type locality is Lima, where Tschudi obtained three specimens from houses, so that it appears to be reasonably abundant. Darwin obtained a specimen from Lima, recorded by Boulenger (1893, p. 36), which presumably belongs here, as may a specimen from Chimbote reported by Cope (1877, p. 35). Boidae Constrictor constrictor ortonii Cope Boa ortonii Cope, Proc. Amer. Phil. Soc., 17, p. 35, 1878 Chilete, near Pacasmayo. Constrictor constrictor Dunn, Proc. Biol. Soc. Wash., 36, p. 186, 1923 Perico and Rio Maranon. A medium-sized boa constrictor, pale in coloration in association with its desert habitat, related to C. c. imperator in the relatively low number of dorsal scale rows. It differs from imperator of Central America and northwestern South America in having a higher number of ventrals and in its lighter and more sandy ground color. The range of C. c. ortonii appears to extend from Perico and the upper Maranon Valley to Piura and south to Libertad, in the arid region of northwestern Peru. The two specimens in Field Museum, No. 8360, from Parinas Valley, Piura, and No. 34301, from Chiclin, Libertad, are both males, with dorsal scales 57-62 at mid-body, ventrals 250-251, and caudals 46-55. The five specimens collected by the late G. K. Noble for the Museum of Comparative Zoology, Nos. 17664 and 306 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. 24 18960, from Perico, and Nos. 18977-18979 from the Rio Maranon, include three males and two females. The total ventral range in males is 246-252, and caudals 46-59. In two females, the ventral range is 246-248, caudals 49-51. The maximum of dorsal scale rows in both sexes is 72. The separation of the orbital scales from the labials in the type, thought by Cope to distinguish this form, holds in several of our specimens, but is not diagnostic. Colubridae 1 Dryadophis boddaertii heathii Cope Drymobius heathii Cope, Journ. Acad. Nat. Sci. Phila., 8, p. 179, 1876 Valley of Jequetepeque; Proc. Amer. Phil. Soc., 17, p. 34, 1877. Herpetodryas boddaertii var. heathii Boettger, Ber. Senck. Ges., 1889, p. 313, 1889. Dryadophis heathii Stuart, Misc. Publ. Mus. Zool. Univ. Mich., 49, p. 77, 1941. The common Dryadophis of the Peruvian coastal region is a medium-sized grayish-colored ground snake, with a light lateral stripe on each side. It is distinguishable from the race D. b. bod- daertii of the Amazon Basin by the position of the lateral stripe on scale rows 4, 5, and 6 anteriorly and 3, 4, and 5 posteriorly, instead of on 4 and 5 only. The young are crossbarred. The subspecies heathii is confined to the Peruvian coastal region, ranging from Libertad to Lima and from sea level to at least 6,000 feet altitude. The specimens examined in Field Museum collections are No. 5706, from Pacasmayo, collected by W. H. Osgood and M. P. Anderson in 1912; Nos. 34283, 34296-34299, 34312, and 34316-19, from Chiclin; and No. 38108, collected at Surco, and presented by Dr. Marshall Hertig. In this series, four male specimens have ventrals 176-185 and caudals 103-107; five females have ventrals 189-192 and caudals 103-108, thus altering Stuart's diagnosis of heathii by a slight lowering of the range of caudals and a considerable lowering of that of the ventrals. This is not surprising, in view of the small number of specimens of this form previously available. The color- 1 Jan's record of Rabdosoma badium multicinctum (Icon. Gen. Ophid., Livr. 10, pi. 4, fig. 5, 1865), from Lima, is not included. It is doubtless based on a transported specimen. 1943 PERUVIAN SNAKES SCHMIDT AND WALKER 307 ation of the under surface is not always immaculate; it may be dotted with gray, and the limit of the encroachment of the dorsal ground color upon it is faintly marked by a narrow whitish line on each side. These changes tend to reduce the differences between heathii and boddaertii, and we have accordingly placed heathii as a race of boddaertii. The series before us includes four specimens from Chiclin with the typical juvenile crossbarred coloration of the boddaertii group (Stuart, 1941, p. 21). A fifth specimen, No. 38108, a male, from Surco, Lima, taken at an altitude of 6,000 feet, measures only 275 mm. in body length, but has no trace of the juvenile markings. We agree with Stuart (I.e., p. 73) in suspecting that there may be a dwarfed Andean race, or that both 6. heathii and 6. boddaertii may be dwarfed at altitudes above their normal range. Stuart (I.e., p. 70) reports a specimen from Huaraz, in the coastal drainage, as boddaertii boddaertii. On geographic grounds, we question this allocation of the specimen. Drymarchon corals melanurus Dume*ril and Bibron Spilotes melanurus Dumeril and Bibron, Erp. G6n., 7, p. 224, 1854 Mexico. Spilotes pullatus dichrous Dunn, Proc. Biol. Soc. Wash., 36, p. 186, 1923 (not of Peters, part). Drymarchon corais melanurus Ruthven, Misc. Publ. Mus. Zool. Univ. Mich., 8, p. 65, 1922; Parker, Ann. Mag. Nat. Hist., (11), 2, p. 443, 1938. Drymarchon corais melanurus is a large terrestrial snake, charac- terized by black coloration on the head and neck and on the posterior part of the body and tail, with the dorsal scales in slightly oblique rows. Its presence in coastal Peru rests on the somewhat dubious record from Chongollapi, Piura (Dunn, 1923, p. 186), but further records from the Catamayo Valley in Ecuador (Parker, 1938) make its occur- rence in the arid coastal region probable. We do not find characters to differentiate this form from the Mexican and Central American melanurus, but it is evident that the Peruvian and Ecuadorean population affords a taxonomic problem, especially in view of the various races of corais in Mexico demonstrated by Smith (1941, p. 466). The Chongollapi specimen has 214 ventrals and 75 caudals. It apparently represents the southern extreme of a trend toward lower numbers of ventrals, which has been pointed out by Smith. 308 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. 24 We are not convinced of the desirability of nomenclatural changes on the grounds offered by Smith (1941, p. 474); see Harper (Copeia, 1942, p. 180) for the contrary argument. It is evident that a malevolent person, applying the interpretation of the rules as followed by Smith, could upset a very large proportion of current names. Dromicus angustilineatus sp. nov. Dromicus chamissonis Schmidt and Walker, Field Mus. Nat. Hist., Zool. Ser., 24, p. 283, 1943 (in part, not of Wiegmann). Type from Toquepala, Tacna, Peru. No. 45908 Museum of Comparative Zoology. Adult male, collected in April, 1938, by W. F. Walker, Sr. Diagnosis. A Dromicus allied to chamissonis of coastal Chile, but with ventrals 204-217 (maximum known in chamissonis 200) and with a narrow dark mid-dorsal line instead of the wider band of the Chilean form. Description of type. Form of body typically colubrid; rostral broader than deep, just visible from above; internasals shorter than pref rentals; frontal twice as long as broad, longer than its distance from the tip of the snout, as long as the parietals; supra- oculars nearly as wide as the frontal; nasal divided; loreal longer than deep; preocular single, reaching the upper surface of the head, but not in contact with the frontal; 2 postoculars on each side; temporals 1-2 on each side; upper labials 8, fourth and fifth entering the eye; lower labials 10, six in contact with the chin shields; pos- terior chin shields longer than the anterior; dorsal scales smooth, with single apical pits, scale reduction formula 19-17-15, the scale rows at mid-body 19; ventrals 204; anal divided; caudals 111. Posterior maxillary teeth enlarged. Hemipenis bifurcate, with bifurcate sulcus and with tips of the bifurcations calyculate. A mid-dorsal dark line three scales wide on the nape soon nar- rowing to the width of the mid-dorsal scale row; a light gray band extending to the fifth scale row, bounded below by a sharply marked though somewhat interrupted black line on the middle of that scale row; a more obscure dark line along the middle of the light gray band; darker gray on the sides, merging below into the lighter ventral color; head brownish above, with a dark streak from the rostral through the eye and across the temporals to become con- tinuous with the lateral darker gray band. 1943 PERUVIAN SNAKES SCHMIDT AND WALKER 309 Notes on paratypes. In addition to M .C .Z . No. 45907 from the type locality, we have examined six specimens in the collection of the University of Arequipa (Schmidt and Walker, 1943, p. 283), of which four have now been accessioned by Field Museum as Nos. 40035- 40038. Three of these, F.M.N.H. Nos. 40037-40038 and U.A. No. 141, are said to be from Madre de Dios, in Amazonian Peru; this we regard as a mistake caused by confusion of data. The remaining paratypes are from Tambo, F.M.N.H. No. 40035; from the vicinity of Arequipa, F.M.N.H. No. 40036; and from the Vitor Valley, U.A. No. 10. This series of specimens, though much faded from exposure to light, agrees well with the type. Two have 21 scale rows on the neck; one has upper labials 7-8, and one has upper labials 9-9; anterior temporals 2 in two specimens; four males have ventrals 195-204, caudals 111-125; three females have ventrals 205-217 and caudals 110-111. The narrow black lines of the back tend to be broken into series of spots, but are distinct in six paratypes; in M.C.Z. 45907 they have disappeared entirely. Measurements. Type 584; tail 161. Largest female (U.A. 10) 891; tail 280. Range. Southwestern Peru, from near sea level to about 10,000 feet. Remarks. It seems evident that Dromicus angustilineatus is directly related to D. chamissonis of Chile, which it replaces in southern Peru, and from which it differs in its higher number of ventrals, and in the narrow dorsal line, instead of the broad dorsal band of the Chilean species. Dromicus tachymenoides sp. nov. Type from Chucurapi (near Mollendo), Department of Arequipa, Peru. No. 34261 Field Museum of Natural History. Adult female, collected in October, 1939, by Colin C. Sanborn. Diagnosis. A Dromicus allied to D. chamissonis of Chile and to angustilineatus described above; differing from the former in its higher number of ventrals (202-220) and from the latter in having a spotted coloration, without longitudinal lines and bands. Description of type. A snake of typical colubrid proportions; rostral nearly as deep as broad, visible from above, internasals shorter than the prefrontals, frontal nearly twice as long as broad, a little longer than its distance from the end of the snout, and nearly as long as the parietals; supraoculars large, as wide as the 310 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. 24 frontal posteriorly; nasal divided; loreal nearly twice as long as deep; preocular single, extending to the upper surface of the head, not in contact with the frontal; 2 postoculars; temporals 2-2 on each side; supralabials 10 on the left side, fifth and sixth entering the eye, 8 on the right, fourth and fifth entering the eye; several labials horizontally divided; lower labials 11-13, 7 and 6 in contact with the chin shields. Dorsal scales smooth, with single apical pit, scale rows 19 at mid-body, 23 immediately behind the head, full formula 23-21-19-17-15; ventrals 202, anal divided, caudals 107. Posterior maxillary teeth enlarged, not grooved. General coloration light gray (superficial epidermis lacking), with black punctulation on most scales; two parallel rows of paired black or dark gray spots along the back, the pairs uniting anteri- orly to form transverse bars on the neck; venter mottled gray and yellow. Head brownish gray above, with a dark gray band from the rostral through the eye to the neck, not in contact with the anterior dark crossbars; labials and chin yellowish, slightly mottled with gray. Measurements. Total length 1,055; tail 300. Notes on paratypes. Two paratypes received from the Uni- versity of Arequipa agree excellently with the type in scale and color characters. Both are females; F.M.N.H. No. 40033 is without data; U.A. No. 15 is said to be from the "Selvas de Sandia," a locality that we regard as an error in labeling. The former specimen has ventrals 220, caudals 106; in the latter the ventrals can not be counted; it has caudals 102. The edges of the ventrals are dotted with black in both specimens. A third paratype, M.C.Z. 45940, is from Toquepala. It agrees in coloration but has a somewhat broader rostral, longer frontal, and shorter loreal than the type; it has ventrals 216, and caudals 95. Range. Known only from southern coastal Peru, where it occurs together with angustilineatus, from sea level to ten thousand feet altitude. Remarks. It will be seen that the numbers of ventrals and caudals in tachymenoides are little different from those in angusti- lineatus; the species appears to be adequately distinguished by its spotted and crossbarred color pattern, which bears a general resem- blance to that of Tachymenis peruviana. It is obvious that the range and habitat of Dromicus angustilineatus and of D. tachy- menoides afford unsolved geographic problems. 1943 PERUVIAN SNAKES SCHMIDT AND WALKER 311 Boigidae Leptodeira larcorum sp. nov. Sibon annulatum (not of Linnaeus) Cope, Proc. Amer. Phil. Soc., 17, p. 33, 1877 Chimbote Valley. Leptodeira annulata Dunn, Proc. Biol. Soc. Wash., 36, p. 186, 1923. Type from Chiclin, Libertad, Peru. No. 34302 Field Museum of Natural History. A male specimen, presented to the Magellanic Expedition of Field Museum by Sr. Constante Larco Hoyle, in 1939. Diagnosis, A Leptodeira resembling L. rhombifera of Central America and northwestern South America in having vertebral and para vertebral scale rows little if at all enlarged, and thus differing from L. annulata annulata; differing from rhombifera in having a higher number of ventrals, 175-184 versus 158-178, and caudals, 78-91 versus 64-84, and in the strong tendency for the dorsal spots to fuse into a zigzag line (in the latter respect resembling annulata annulata; Dunn, 1936, p. 691). Description of type. A snake with large head, distinct from the neck, with a large eye; body slightly compressed. Rostral much broader than high, scarcely visible from above; internasals shorter than the prefrontals; frontal one-third longer than broad, as long as its distance from the end of the snout, shorter than the parietals; nasal divided; loreal slightly longer than high; a large preocular, in contact with the frontal; a small inferior preocular formed by divi- sion of the third labial; 2 postoculars; temporals 1-2, with a small additional anterior temporal cut off from the seventh labial; upper labials 8, the fourth and fifth entering the eye; lower labials 10, six in contact with the chin shields; posterior chin shields slightly longer than anterior; dorsal scales smooth, simplified formula 19-21-15; ventrals 184, anal divided, caudals 91. Head grayish brown with a butterfly-shaped darker marking on the parietals and occiput, and a dark band from snout to angle of mouth; grayish brown above, with alternating para vertebral blotches that tend to fuse into a zigzag dorsal band; a lateral row of alter- nating spots, with still smaller spots on the first and second scale rows; lateral spots disappearing on the tail; uniform yellow beneath, with faint brown markings on the chin and lower labials. Measurements of type. Total length 630; tail 172. Notes on paratypes. Twenty-three specimens in addition to the type are referred to this species: F.M.N.H. Nos. 34306-34311, from the type locality, presented by Sr. Constante Larco Hoyle; M.C.Z. Nos. 312 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. 24 17412-17416 from Perico, and 17454-17465 from Bellavista, collected by G. K. Noble in 1916. In this series, in excellent agreement with the type in coloration, the preocular is in contact with the frontal in about half the specimens, and several agree with the type in the presence of a small lower preocular, and in the small supernumerary anterior temporal. There is some geographic variation in the caudals in females, not discernible in the smaller series of males, as shown below: Number of specimens Sex Ventrals Caudals Coastal series / 3