OCR Text |
Show 858 A> PEffDIX C.- RtfrtlLBS. reduced and concealed. On specimens- preserved in alcohol they are found as distinctly marked aa in PAr. douglatiii of plate VII, fig. 10. . • IF we compare now Phr. douglasrii with the'two preceding ones, • its rounded and anteriorly truncated head gives to it a peculiarly different aspect. The reduced cephalic spinas constitute another feature quite as striking, especially when combined with the aspect of . the upper surface ( fig. 6). The lower, surface of the head, being covered with uniform scales, there is no possibility of mistaking it either for Phr. cornuhyn, which has a row of larger* 6cales extending from the chin to the throat* or for Pht. coronatum, in which th$ dissimilarity in the shape of these scales is still greater. PArynosdma ptytyrhirio* seems at first very similar to Phr. dougUntil,' on account* no doubt, of the. small'development of the cephalic spines and t| ie uniformity of the scales of the lower surface of the head. But we need only compare the vertex, the occipital plates ( fig. 1 and 6) » the margin of the lower jaw ( fig* 3 and 9), the profile ( fig. 2 and 7), and the position of the nostrils ( fig. 4' and 0), in order to become satisfied of the specific distinction between these two species. , The chief difference between Phr. modettum and Phr. platyrhino* are not to be found prominent in the head, but rather in the general structure of the body and tail. The specimen which we have had figured being a young- one, these differences might appear too < trifling. But recently we have received from Colonel « L D. Gra-lam,, a series of full- grown individuals,' by which it can be shown that this species, which we had distinguished from the others upon an immature specimen, appears still more distinct upon the examination of the adults. In comparing attentively the figures Vhich we now give of Phr. modestum, the differences, will appear ' evident. The vertex is much more inclined forward in Phr. modestum ( PkVH. fig. 2) than m Phr. platyrAinot, ( PLVI. fig. 6). The, plates which line the margin of " both the. upper and lower jaws are likewise different, as well as the stales of the inferior surface of thti head, Which are proportionally, smaller in Phr. modestum than in Phr. plaiyrhinos. Of Phr. ctrbiculare we have 6een only two specimens, and these Were young individuals. . But there is something so striking in its features as to enable us at once to distinguish it from its congener. Its snout is flattened, and the extremities of the jaws much more protruded than in any other species.; it therefore differs greatly |