CROCODILIANS, LIZARDS, AND SNAKES. 



243 



process is median, short, and deourved. The iscliia have a long, com- 

 mon suture, and are deflected downward, meeting at less than a right 

 angle. Tuber a prominent angle. The ilium presents a short subacute 

 angle, representing the crista. There is a deep posterior notch of the 

 acetabulum. 



In Dipsosaurus dorsaUs all the teeth on the maxillary bone are tri- 

 cuspidate; those on the premaxillary are mostly simple, but one or two 

 external ones show a rudimental lateral cusp. 



In the only known species the colon is well developed, and the small 

 intestine is elongate. Its habits are herbivorous, as I have taken 

 remains of flowers from their stomachs. 



DIPSOSAURUS DORSALIS Baird and Girard. 



Dipsosaurus dorsalis Hallowell, Proc. Acad. Nat. Sci. Phila., VII, 1854, p. 92; 



Kept. U. S. Expl. Surv., XIII, Pt. 4, p. 7, pi. vi, fig. 1.— Baird, U. S. Mex. 



Bound. Surv., Herp., 1859, p. 8, pi. xxxii, figs. 7-13.— Bocourt, Miss. Sc. 



Mex., Kept., 1874, p. 146.— Boulenger, Cat. Liz. Brit. Mus., 2d ed., 188.5, II, 



p. 201.— Van Denburgh, Proc. Cal. Acad. Sci., 1895, p. 92. 

 Crotaphytus dorsalis Baird and Gikard, Proc. Acad. Nat. Sci. Phila., 1852, p. 126. 



Fig. 18. 



DirsosAURus DORSAUS Baird and Girard. 



Xf. 



Fort Yuma, Arizona. 



Cat. No. 2730, U.S.N.M. 



Head small, scarcely as wide as the neck, or more than half the 

 length of hind foot; rather longer than broad; muzzle blunt: forehead 

 sloping very rapidly. A single gular fold. The scales on the chin 

 large, granular, and nearly even. A conspicuous ridge on the back 

 from head to middle of tail, formed of a single series of scales larger 



