44, pETROSAURUS.—45. CALLISAURUS. 205 
44, PETROSAURUS. 
Tympanum distinct. Body depressed; no dorsal crest; dorsal 
scales small, granular, smooth, uniform. Upper head-scales a little 
enlarged, occipital very large. Two strong transverse gular folds 
without denticulation; no gular sac. Digits with keeled lamelle 
inferiorly. A long series of femoral pores. Tail long, feebly de- 
pressed. Lateral teeth tricuspid; no pterygoid teeth. A sternal 
fontanelle. No abdominal ribs. 
Lower Calfornia. 
1. Petrosaurus thalassinus. 
Uta thalassina, Cope, Proc. Ac. Philad. 1863, p. 104. 
Head rather small, snout narrowed; nostril large, superior, 
equally distant from the orbit and the end of the snout; ear- 
opening large, oval, with a denticulated lobe of skin anteriorly ; 
head-scales smooth; a single scale in the middle between the 
orbits ; three longitudinal series of supraocular scales, surrounded 
by granules ; occipital nearly as large as the tympanum; a large 
infraorbital; upper labials seven or eight, very low; lower labials 
larger. Throat granular, with two strong transverse folds, the 
anterior forming a small pouch on each side; a third, less marked, 
anterior fold; sides of neck strongly plicate. Dorsal and lateral 
scales uniform small, convex, smooth granules; ventrals larger, flat, 
squarish or hexagonal. Limbs moderate, with larger keeled scales; 
the adpressed hind limb reaches the tympanum ; digits strong, com- 
pressed. Sixteen or seventeen femoral pores on each side. Tail 
slightly depressed, slender, covered with rings of small, squarish, 
obliquely keeled scales ; its length once and a half that of head 
and body. Olive above, fore limbs and anterior part of back with 
a fine black network; back with transverse series of pale greenish 
spots alternating with dark cross bands, of which the three anterior 
are of an intense black, bordered with pale greenish posteriorly ; 
tail with darker and lighter cross bars; lower surfaces greenish 
white, throat blackish. 
millim millim 
Total length ...... 311 Fore limb ........ 52 
Head .-sccec ees ds 30 Hind limb........ 81 
Width of head.... 23 Pail 2 edans sg areca te aeyies, 185 
Body ie Varese oats 96 
Lower California. 
ao. Cape St. Lucas. Smithsonian Institution [P.]. 
45, CALLISAURUS. 
Callisaurus, Blainv. Nowy. Ann. Mus, iv. 1835, p. 286; Dum. § Bibr. 
iv. p. 824; Gray, Cat, Liz. p. 226; Bocourt, Miss. Sc. Mex., Rept. 
158, 
p- 
