80 CROTAPHYTUS COLLARIS. 



Description. The head is short, thick, and sub-triangular, with the snout 

 rounded; the forehead arched above, sloping suddenly downwards, and with the 

 temporal regions swollen or greatly developed; the forehead, vertex, and occiput 

 are covered with numerous small polygonal plates, smooth, and all nearly of the 

 same size, becoming only a little more minute as they approach the nostrils and 

 margin of the upper jaw. The superior face of the orbit is covered with many 

 small polygonal plates, disposed without order in general, but on the outer margin 

 is a row of scales distinct, though not of larger size. 



The nostrils are placed on a line with the superciliary ridge; they are lateral, 

 large, open in a single plate, which is somewhat elevated, so as to make them 

 appear slightly tubular, and are surrounded by several small plates; the openings 

 are rather large and are directed upwards, outwards and backwards. * 



The upper jaw is covered with twenty-four small, quadrilateral, labial plates, 

 above which are two or three rows of smaller plates, though of nearly similar 

 form. The rostral is quadrilateral, greatly elongated transversely, so as to 

 appear like two ordinary labial plates united in one. The mouth is rather small, 

 and the tongue broad, slightly notched at its tip, and covered with fungiform 

 papillae. The upper jaw is armed with eighteen teeth; six incisors, two longer 

 canine; the seven posterior being compressed laterally and tricuspid at their 

 cutting margins. The lower jaw has fourteen teeth; and the palate is provided 

 with minute teeth, and there are several rather large, distinct and conical in the 

 sphenoidal bone. 



The orbit before, below and behind is bordered with ten or twelve small quadri- 

 lateral plates, those below are rather largest, and slightly concave; between these 

 plates and the lids are several rows of minute plates or granulations. Of the 

 eyelids the superior is largest, and both ai-e covered with minute granulations, and 

 have at their tarsal margins a row of quadrilateral plates, larger in the lower, and 

 having a second row of smaller plates attached to their outer border, which makes 

 a remarkably serrated margin. The eyes are rather large, but appear less so 



