CROTAPHYTUS COLLARIS. 81 



because of the projection of the superciliary border; tlie pupil is black, round, 

 and the iris silvery. 



The external opening of the ear is long, narrow, quadrilateral, most extensive 

 vertically, and surrounded with small scales, of which four or five in front are 

 conical, and project a little backwards, so as to give a slightly notched 

 appearance to the middle of the anterior border. The membrane of the 

 tympanum is visible, though deeply placed, and is extended nearly from without 

 inwards. The chin and throat are covered with small, nearly equal sized plates, 

 smooth, and not imbricated. The neck is contracted, with a transverse fold 

 ascending on each side, in front of the shoulders. The body is large, elongated, 

 depressed, rounded at the flanks, and covered above with small, sub-hexagonal 

 scales, either roxmded or a little oblong, neither imbricated nor carinated, all 

 nearly of the same size, and "obsoletely arranged in transverse lines." The 

 thorax and abdomen are protected by larger plates than the back, though still of 

 small dimensions, smallest on the thorax; they are of quadrate form, or slightly 

 sub-hexagonal, imbricated, and are distinctly arranged in transverse series. 



The anterior extremities are large, and covered above with small scales, 

 similar to the back, and below with scales still smaller, while in front there are 

 but few larger, variable in form, and imbricated. There are five distinct, ^\ell- 

 developed fingers; the third and fourth of the same length, all much compressed 

 laterally, scaled to the roots of the nails by a single transverse row beneath, and 

 by two or three rows above. Each finger is furnished with a nail — small, short, 

 curved, pointed, and much compressed. 



The posterior extremities are also large, and covered like the anterior above 

 and below; though the plates are small, they vary much in form; they are smooth, 

 rhomboidal, or sub-triangular, imbricated, and largest on the leg. The tarsus is 

 covered with larger imbricated scales above, and sustains five long, laterally- 

 compressed toes, covered like the fingers, and furnished with nails of similar 

 Vol. II.— 11 



