40. wopLocercts,—41. pipsosauRUs. 201 
tubercles, alternating with severa] 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. 
millim, millim 
Total length ...... 141 Fore limb ........ 26 
Head............ 17 Hind limb........ 42 
Width of head .... 12 Daal. sarin em ita sees 80 
Body ize aie iad Youths 44 
Ecuador. 
ad. Canelos. Mr. Buckley [C.]. (Type.) 
41. DIPSOSAURUS. 
Dipsosaurus, Hallow. Proc. Ac, Philad. 1854, p. 92; Bocourt, Miss. 
Sc. Mex., Rept. p. 146. 
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 lamella 
inferiorly. A long series of femoral pores. Tail long, cylindrical. 
Lateral teeth tricuspid; pterygoid teeth. No sternal fontanelle. 
No abdominal ribs. 
South-western North America. 
1. Dipsosaurus dorsalis. 
Crotaphytus dorsalis, Baird § Gir, Proc. Ac, Philad, 1852, p. 126. 
Dipsosaurus dorsalis, Hallow. . v., and Rep. U.S. Expl. Surv. xiii. 
pt. iv. p. 7, pl. vi. fig. 1; Baerd, U.S. Mex. Bound. Surv., Herp. 
pl. xxxii. figs. 7-13 ; Bocourt, lc. 
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; an 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 oblique, 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 semiannulated with darker and 
lighter; lower surfaces white, the throat with narrow, oblique 
bluish streaks. 
