17. PRISTIDACTYLUS.—18. sCARTISCUB. 127 
17. PRISTIDACTYLUS. 
Leiosaurus, part., Dum. § Bibr. iv. p. 241. 
Pristidactylus, Fiteing. Syst. Rept. p. 58. 
Ptenodactylus, Gray, Cat, Liz. p. 224. 
Tympanum distinct. Body depressed, covered with small smooth 
scales, granular on the back; no dorsal crest. Two transverse 
gular folds; no gular pouch. Digits depressed, with bi- or tri- 
carinate lamelle inferiorly, the toes serrated on their inner border. 
No femoral pores. Tail long, rounded. Lateral teeth tricuspid ; 
pterygoid teeth. 
Patagonia. 
1. Pristidactylus fasciatus. 
Leiosaurus fasciatus, Gray, Cat. p. 224. 
Leiosaurus fasciatus, D’ Orb. Amér. Mér., Rept. p. 8, pl. iii. figs. 5-7 ; 
Dum. § Bibr, p. 244. 
—— (Pristidactylus) fasciatus, Fitzing. lc. 
In habit similar to Liosaurus belliz, but the tail nearly twice as 
long as the body. Only two series of scales between the orbits. 
Greyish above, with broad, transverse, dark brown bands; a large 
deep black spot on each shoulder; lower surfaces white, chest. and 
belly with traces of brown cross streaks. 
From snout to vent 44 millim, 
Rio Negro, N. Patagonia. 
18. SCARTISCUS. 
Scartiscus, Cope, Proc. Ac. Philad. 1862, p. 182. 
Tympanum distinct. Body depressed; a median dorsal keel. 
Dorsal scales large and imbricate. Upper head-scales small. No 
antepectoral fold. Digits strongly pectinate inferiorly. No femoral 
or preanal pores. Tail slender, compressed, covered with appressed 
equal verticils of weakly keeled scales. No pterygoid teeth. Ab- 
dominal ribs. 
Paraguay. 
1. Scartiscus caducus. 
Scartiscus caducus, Cope, J. e. 
Head-scales numerous, small, keeled; nostrils lateral, below the 
canthus rostralis. A slight preaxillary fold. Median dorsal keel 
forming a low crest on the nape. Scales of the body large, flat, 
caducous, keeled everywhere; the dorsal in posteriorly convergent 
series. The adpressed hind limb reaches the anterior border of the 
orbit. Third and fourth toes nearly equal. Colour above brown, 
with numerous dark brown chevrons, the angles directed posteriorly ; 
a narrow, vertical, yellow line from the axilla; extremities and tail 
cross-banded; beneath yellowish brown, the throat darker, light- 
varied. 
