17. PRISTIBACTYLUS. 18. SCAETI8CU8. 127 



17. PRISTIDACTYLUS. 



Leiosaurus, part., Dum. i^- Bibr. iv. p. 241. 

 Pristidactylus, Fitzing. Syst. Hept. 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 lamelloe infcriorly, the toes serrated on their inner border. 

 No femoral pores. Tail long, rounded. Lateral teeth tricuspid ; 

 pterygoid teeth. 



Patagonia. 



] . Pristidactylus fasciatus. 



Leiosaurus fa.sciatus, Gray, Cat. p. 224. 

 Leiosaurus fasciatus, IJOrb. Amer. Mcr., Hept. p. 8, pi. iii. tigs. 5-7 ; 



Dum. f Bibr. p. 244. 

 (Pristidactylus) fasciatus, Fitzing. 1. c. 



In habit similar to Liosauras bellii, 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. 18G2, 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 inferiorlJ^ No femoral 

 or prceanal 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, I. c. 



Head-scales numerous, small, keeled ; nostrils lateral, below the 

 ctmthus rostralis. A slight preaxillary fold. Median dorsal keel 

 forming a low crest on the nape. Scales of the body largo, flat, 

 caducous, keeled everywhere ; the dorsal in posteriorly convergent 

 series. The adprcssed hind limb reaches the anterior border of the 

 orbit. Third and fourtli toes nearly equal. Colour above brown, 

 witli numerous dark brown chevrons, tlie angles directed posteriori}' ; 

 a narrow, vertical, yellow line from the axilla ; extremities and tail 

 cross-bandod ; beneath yellowish brown, the throat darker, liglit- 

 varietl. 



