OCR Text |
Show APPENDIX C.- REPTILES. 355 temporal region is very much developed and projects over the auditory aperture, and is provided along its projecting margin with spines or conical plates, the largest of which is most approximated to the occiput. The eyes seem as if situated in the middle of a groove extending from the snout to the occiput, on account of the projection of the superciliary ridge and temporal region. The lower jaw is generally bordered with a row or two of large plates, which vary in structure and shape according to the species, and furnish good discriminating characters between them. The snout is either truncated or acute. The nostrils are conspicuous, and situated near the extremity of the snout, either within the inner margin of the superciliary ridgp, or on its direct prolongation. The upper surface of the head and sides not occupied by the spines or tuberculous knobs, are covered with small polygonal plates, varying in size according to the area over which they extend. The surface of these plates is rugose, wrinkled or keeled, as is also the surface of the spines themselves. They are exceedingly small in advance and behind the orbits. The whole surface of the eyelids is covered with minute scales of a granular appearance; the margin of the eyelid itself is ornamented with a double row of sub-quadrangular plates, a little larger than the granules of its surface. The lower part of the head from the chin to the breast is covered with small scales, characteristic in each species. The neck is generally very short, appearing as if contracted, the result of which contraction would be the presence of several folds of the skin, concealing the auditory apertures in conjunction with the temporal projection of the head. The scales on the upper surface of the body are very irregular in size and shape; on the neck, above and below, on the pits, along the sides of the back, and on the groins, they assume a granular appearance, while along the middle of the back and on the tail they appear like thin lamellae, very irregular still, and cari-nated or subcarinated. All over the back, sides, tail, and hind legs, there are large, irregularly pyramidal scales, with an acute point and a wrinkled or carinated surface. The margins of the abdomen exhibit one or two horizontal rows of these pyramidal but soft scales, bent backward, extending from the fore legs to the hind ones. The species in which the scales of the back are the largest, is Phr. coronatum, which strikes every one by its rough appearance ; while those in which the scales are the least developed are Phr. platyrhinos and Phr. modestum, whose external appearance |