OCR Text |
Show 1878.] CLASSIFICATION OF THE CERVIDAE. 897 (15) The antlers of the Cervidae are subject to great variation ; and such variations are transmissible by heredity. (16) Two species have a circumpolar range, and Cervus canadensis, a species allied to the common Red Deer of Europe, is found in North America. Facts (continued). Hypothesis (continued). attributed to the same cause. (14) There are only twenty- (14) The Deer of South Ame-two species in America ; and the rica, which, according to the South-American species have theory under consideration, have remarkably simple antlers. been freer from contact with allied forms than species inhabiting districts nearer to, and more in direct continuity with, the centre of the family area of distribution, are remarkable for the great simplicity of their antlers. (15, 16) For long periods there was no possibility of communication between the Deer of the Old and New World ; and during this time the perpetuations by heredity of the more favourable varieties which arose from time to time resulted in the divergence of the Cervidae into the clusters of species which we now term genera. (16) At length the means of dispersal was for a second time opened between Asia and North America; an interchange of species took place; the ancestors of Cervus canadensis passed over into North America from the Old World, and the Elk and Reindeer extended their range till it was circumpolar. In the following synopsis I have admitted every species of whose invalidity I am not absolutely certain ; and frequently, even where I have felt grave doubts as to the soundness of the claims of a species to specific recognition, I have left it distinct, if by so doing I have thought it probable that future investigation of its claims may throw light on the important problems of geographical variation and distribution. Where colour is not mentioned in the diagnoses it affords no generic or subgeneric character. Supplementary columns are absent in the molars, and the central incisors are much expanded, where the contrary is not stated. Where the metatarsal and tarsal tufts are not specially mentioned, they are present. V. Synopsis of the existing Cervidae. A. Proximal ends of lateral metacarpals remaining. (PLESIOMETACARPI.) Posterior portion of the nasal cavity not divided by the vomer into two distinct chambers. |