40. HOPLOCERCCS. 41. mPSOSAURUS. 201 



tubercles, alternating with several series of minute scales ; sub- 

 caudal scales less unequal and keeled. Brown, with transverse 

 blackish bands on the back ; an oblique yellowish band on the 

 shoulder ; lower surfaces brownish white, neck dark brown. 



minim. millim. 



Total length 141 Foro limb 26 



Head 17 Hind limb 42 



Width of head 12 Tail 80 



Body 44 



Ecuador. 

 a. d . Canelos. Mr. Buckley [C.]. (Type.) 



41. DIPSOSAUEUS. 



Dipsosaurus, Halloiv. Froc. Ac. Philad. 1854, p. 92 ; Bocourt. Miss. 

 Sc. Mex., Rept. p. 14G. 



Tympanum distinct. Body subcylindrical ; a small dorsal crest ; 

 dorsal scales small. Upper head-scales small. A strong transverse 

 gular fold ; no gular pouch. Digits compressed, with keeled lamellae 

 interiorly. A long series of femoral pores. Tail long, cylindrical. 

 Lateral teeth tricuspid ; pterygoid teeth. No sternal foutanelle. 

 No abdominal ribs. 



South-western North America. 



1. Dipsosaurus dorsalis. 



Crotapbytus dorsalis, Baird ^- Gir. Proc. Ac. Philad. 1852, p. 126. 

 Dipsosaurus dorsalis, Halloiv. I. c, and Rep. U.S. E.vpl. Surv. xiii. 



pt. iv. p. 7, pi. vi. fig. 1 ; Baird, U.S. Me.x. Bound. Stirv., Herp. 



pi. xxxii. figs. 7-13 ; Bocourt, I. c. 



Snout short, with obtuse canthus rostralis ; nostril lateral, verti- 

 cally elliptic, nearer the end of the snout than the orbit ; upper 

 head-scales small, smooth, convex on the forehead and snout ; supra- 

 ocular scales smaller still ; au elongate infraorbital scute ; labials 

 small ; anterior border of ear denticulated. A dorsal crest of 

 slightly enlarged keeled scales. Dorsal scales small, keeled, rhom- 

 boidal, juxtaposed, the keels obHque, directed towards the dorsal 

 line ; ventral scales imbricate, smooth. Digits moderately long. 

 Twenty-two or twenty-four femoral pores on each side. Tail [twice as 

 long as head and body] covered with equal small keeled scales, forming 

 rings, and a median series of larger scales, forming a serrated ridge. 

 Brownish above, with black reticulation enclosing whitish sub- 

 circular spots on the sides ; tail semianmdated with darker and 

 lighter ; lower surfaces white, the throat with narrow, oblique 

 bluish streaks. 



