CROCODILIANS, LIZARDS, AND SNAKES. 241 



of liead at auricular meatus, 42 uim.; width of bead above auricular 

 meatus, 35 mm. ; leiiytb of auterior limb, 93 mm. ; length of anterior foot, 

 37 mm. ; length of posterior limb, 150 mm. ; length of posterior foot, 76 mm. 



I have before me two stuffed specimens of this species, a large one 

 and probably adult, and a smaller and younger one, which I described 

 above. This is No 201 of Sumichrast's collection, and was procured by 

 him at Dondoniingvillo, in the State of Oaxaca, and sent to the Smith 

 souian Institution. The other specimen was obtained near Batopilas, 

 Chihuahua, by Mr. Edward Wilkinson, and was recorded by me as 

 Gyclura acanthura in the catalogue of his collection.' It agrees with 

 the t3'pe specimen in having the distal two-thirds of the tail strongly 

 compressed. The dorsal crest is much less elevated, probably owing 

 to its younger age. The colors are paler, the prevailing tint being light 

 brown with indistinct darker brown cross bands. More recently a 

 specimen was sent to the U.S. National Museum from Xogales, a town 

 which stands on the line between Arizona and Chihuahua. The species 

 is clearly to be included in the area of the Columbian Realm. 



I find a specimen of this species, enumerated as Yar. B of Cte>iosaHra 

 acanthura by liouleuger.'^ 



Ctenosaurtt mullis2)lnifi C(^>e. 



("atalogue 

 No. 



Number 

 of speci- 

 mens. 



Locality. - { Collector. 



17178 



Nogales, Arizoua ; P. L. Jouy. 



DIPSOSAURUS Hallo^ATell. 



IHpsosanrua IIallowell, Proc. Acad. Nat. Sci. Phila., VII, 1851, p. i»2. — Hocourt, 

 Miss. Sc. Mex. Kept., 1874, p. 116.— Boilencei;, Cat. Liz. Hrit. Mus., II, 1885, 

 p. 201. 



A gular fold. Sides of neck wrinkled. Dorsal and ventral scales 

 more or less imbricated, all distinctly rhomboidal, or lozenge-shaped, 

 and in nearly transverse series. Tail much longer than body; much 

 compressed. Back with a crest of a single series of larger, strongly 

 carinated, but not spinous scales. Femoral pores. Nostrils terminal, 

 entirely lateral, anterior to end of canthus rostralis. Palate not 

 toothed, the jmrtion between the posterior uares scooped out. Tongue 

 arrow-shaped, slightly bifid, with two large elliptical, sessile pads. 

 Teeth pleurodent, all compressed, and strongly 3-lobed, even the ante- 

 rior ones. 



But one species of this genus is known. It is of interest as approach 

 ing more nearly in its characters the large arboreal types of tropical 

 America than any other which enters our fauna. 



Osteoloyij. — The osteology of this genus presents a number of inter- 



' Proceedings, American Philosophical Society, XVIII, 1879, p. 261. 

 -Catalogue of Tiizards in tlio British Museum, II, p. 197. 

 NAT MUS 98—16 



