ZOOLOGY REPTILES. 7 



DIMENSIONS. Length of head, neck, and body, 4| inches ; greatest breadth of head, 1 inch ; 

 length, 1 inch ; tail mutilated, circumference at base 1-f- inch ; length of anterior extremities, ! 

 inch ; of foot to extremity of longest toe, % inch ; of posterior extremity, 2^ inches ; of foot, 

 posteriorly, to extremity of longest toe, 1 inch. 



HABITAT. Same. 



DIPSOSAURUS, Hallowell. 



GEN. CHAR. Head triangular, small, covered above and in front with tubercles, those upon 

 the front the largest ; gape of the mouth moderate, its posterior extremity on a line with the 

 posterior margin of the orbit ; eyelids covered with granulations, their edges with scales pre 

 senting a denticulated margin ; a row of narrow, oblique,imbricate scales over the orbit ; scales 

 upon orbit polygonal, unequal, the four or five inner rows the largest ; temples covered with 

 smooth polygonal tubercles, of unequal size ; teeth tricuspid, closely set on the inner side of 

 the jaw, the posterior largely developed ; no palatine teeth ; tongue arrow-shaped, slightly 

 notched in front, deeply cleft posteriorly; nostrils latero-superior, opening in a single scale; 

 rostral plate vertical, triangular ; jaws margined each with a series of smooth, quadrilateral 

 plates ; tympanum visibly depressed ; anterior margin of auricular opening denticulated ; upper 

 part of body covered with carinated scales, more or less rounded posteriorly, arranged in oblique 

 rows ; a row of scales much larger than the rest, along the dorsal line and much more strongly 

 carinated, forming a slight dorsal crest ; a gular fold ; scales of abdomen, quadrangular, smooth ; 

 femoral pores, but no anal ones; tail long, cyclo-tetragonal at base, tapering gradually to a point, 

 covered with transverse rows of verticillate and carinated scales. 



DIPSOSAURUS DORSALIS. 



SrN. Crotapliytus dorsalis, Baird and Girard. Proceed. Acad. Nat. Sc. 1852, p. 126. 



SP. CHAK. One hundred and nine scales may be counted in one of the transverse rows running 

 round the body near its middle, and terminating at the larger dorsal row ; scales upon throat 

 much smaller than those upon chin and abdomen ; scales upon upper part of anterior and 

 posterior extremities carinated ; posterior surface of thighs granulated ; the granulations sur 

 rounded with minute granules ; third and fourth finger of nearly equal length ; fourth toe 

 much the longest ; margins of fingers and toes denticulated, inferior surface presenting trans 

 verse rows of carinated scales ; posterior extremities much stouter than the anterior ; sides of 

 neck folded. 



COLORATION. Body presenting numerous lines of red upon the sides, with blotches of the same 

 color over the shoulders, the intervening spaces numerous white spots ; upper surface and sides 

 of tail marked with red spots arranged in transverse rows ; upper surface of extremities with 

 red ; throat, abdomen, under surface of extremities, and tail white. The coloration, as des 

 cribed by Professors Baird and Girard, appears to be taken from young specimens, one such 

 before me corresponding with it precisely. 



DIMENSIONS. Length of head, 7 lines; breadth, 7; length of head, neck, and body, to vent, 

 8 inches, (Fr. ;) of tail, 7^ inches; anterior extremities, 1^ inch; posterior, 3 inches, to extremity 

 of nail of longest toe. 



HABITAT. Desert of the Colorado, to which it appears to be confined. The smaller specimen 



