CROCODILIANS, LlZAltDS, AND SNAKES. 



321 



orly by three very siujiU scales; supraocular scales equal in size, partic- 

 ularly iu the female, four iu number, broader than long, and surrounded 

 by scutella more numerous iu front than ou the other sides. The edge 

 of the muzzle protected by two scales with i^rojecting keel, followed by 

 two overhauging scales, slightly elongated; a long narrow scutellum 

 forms almost the entire suborbital arch ; on each lip there are five or 

 six pairs of plates; the npper ones are surmounted by another row of 

 scales just a little smaller. Mental plate i)entagonal, as wide as it is 

 high, having an acute angle behind; and followed on each of the jaws 

 by rather large scutella, which gradually diminish in size as they recede. 

 Auricular opening large, with the anterior border furnished with small 



Fig. 43. 



UTA BICARINATA DDMI^;RIU 



X 1.5. 



Chihuahua, Mexico. 



Cat. Nil. 14i;48, L'.S.N.M. 



conical scaies, forming a feebly-toothed structure. Under the neck 

 there is a granulated pavement separated from the larger and imbri- 

 cated scales of the chest by the two transverse folds of the neck; the 

 scales of the posterior part of this region are better developed and 

 termituite in points; on the sides of the neck there are wrinkles edged 

 with little tubercles, forming longitudinal ridges, originating back of 

 the ear, one of which is prolonged underneath the arm. Trunk lightly 

 depressed, covered above and on the sides with small scales, almost 

 round, slightly convex, not imbricated, and among which the keeled 

 scales show like small tubercular elevations; scales of the abdomen 

 rather large, smooth, and imbricated. Tail longer than the head and 

 NAT MUS 98—21 



