Miscellaneous. 185 There is a good deal of difference in the shape and form of the blade bone, probably dependent on age. The blade bone of the smaller specimen is subtriangiilar, being about one 10th part wider than it is high from the front of the condyle to the upper edge ; the acromion and coracoid processes are djurected forwards, and only slightly bent outwards ; the acromion is much broader, and rounded at the end. In the larger specimen the blade bone is much wider than high ; that is to say, it is more than once and a half as wide as high ; the coracoid and acromion processes are much elongated and strongly bent upwards. This difference may be sexual ; for the young bone does not appear to be like a portion only of the larger one : and if there is a change of form, the whole bone changes as it grows ; that is to say, the angular prominence on the front edge is lower down the front margin in the larger one. In aU these specimens the bones of the face are shorter than the distance from their edge to the crest round the nostrils ; and in this respect it differs from De Blainville's figure of Physeter breviceps, which is said to have come from the Cape of Good Hope ; but I have never had the opportunity of examining the skuU, and there-fore cannot vouch for the correctness of the figure. A partial Comparison of the Concliology of Portions of the Atlantic and Pacific Coasts of North America. By Robert E. C. Stearics. A striking feature in the conchological fauna of that part of the Pacific coast included in the Californian-and-Vancouver zoological province, when compared with the moUuscan fauna of the Atlantic coast from the arctic seas to Georgia, is the preponderance in the former of those forms of moUuscan life which are embraced in the order of Scutibranchiata*. The Scutibranchiate Gasteropods, or shield-gilled crawlers, com-prise a great number of mollusks, all of which are marine, and which inhabit the sea-shore, principally the littoral and laminarian zones, subsisting on marine vegetation ; thus we find the beautiful group of Calliostoma upon the larger algte, as well as the unique Trochiscus [T. Soiverbi/i), and Chlorostoma crawling over the sedimentary rocks, upon which grows the green Cladophora or some allied vegetable form upon which it feeds, and which also is the favourite food of several species of limpets. The order of Scutibranchiata, according to Messrs. Adams, in-cludes : — the family of Neritidcv (none of which are found in the Californian and Orcgonian province, though they begin to appear on the coast of Lower California) ; the Trochidce, which is largely re-presented by the following genera — Eutropia one si^ecies, Leptothyra three species, Pachypoma and Pomaidax one species each, Liotia cue (perhaps two) species, TJiaJotia and Trochiscus one species each, Ccdliostoma, Chlorostoma, Omphalius, Maryarita, and Gibbula, each by several species ; the family of Haliotidcv, which is represented by several species, all of large size, widely distributed and exceedingly numerous in individuals — Fissnrella, including Lucapina, Qlypliis, * Vide Adams, ' Genera of Recent MoUusca,' vol. i, p. 376. A7in. & Mag. N. Hist. Ser. 4. Vol. xii. 13
BioStor
