SUBORDER B 



LITOPTERNA 



125 



dont. Orbits open posteriorly, nasals short and extending far forward. 

 Manus and pes tridactyl. 



Oxyodonthermm, Scalabinitherium Ameghino. Pliocene ; 



Mt Argentina. Nasal opening above molars. Teeth rather 



<'^viSr"^ hypsodont. 



Macrauchenia patachonica 

 Owen. Manus. i/g. (After 

 Gervais.) 



Macrauchenia Owen 

 (Opisthorhinus Bra v.) (Figs. 

 158-160). Nasals rudi- 

 mentary, a large nasal 

 opening on the centre of 

 the skull. Orbits posteri- 

 orly closed. Pleistocene, 

 Argentina, 



Family 3. 

 Proterotheriidae 



Ameghino. 



Skull rather long with 

 tapering muzzle. Nasals long. 

 Orbits posteriorly closed. 



All teeth hrachyo- 



FiG. 159. 



Macrauchenia patachonica Owen. Pampas formation of Pleistocene, Buenos Aires, 

 Argentina. Inferior and superior aspect of slvull. Ve- (After Bra vard.) 



Fig. ICO. 



Macrauchenia patachonica Owen. Restored skeleton. 

 Much reduced. (After Burmeister.) 



2.1.4.3. 



dont. In the upper jaw a small diastema. Upper molars with \N -shaped ectoloph, 

 two large inner cusps, of unequal size, and one or two secondary cusps. The last pre- 

 molars frequently molariform. Lower molars and P 2-4 with ttvo semicirctdar ridges 

 and four roots. I enlarged, canine small. Extremities with three or one toe, only 



