SUBORDER c ENTELONYCHIA 241 



four upper premolars. Pliostylops Ameghino. With four lower premolars. 



Fig. 325. 



Notostylops murlnus Ameghino. 

 Upper Eocene (Notostylops beds), 

 Patagonia. Skull, palatal aspect. 

 1/3. (After Ameghino.) 



Entelostylops triplicatus Ameghino. Upper Eocene 

 (Notostylops beds), Patagonia. A, Upper cheek 

 teeth. B, Lower cheek teeth. i/i. (After 

 Ameghino.) 



Eomalostijlops Ameghino. With complete dentition. Eostylops, EntelostyloiJS 

 (Fig. 326), etc., Ameghino. Eocene ; Notostylops beds of Patagonia. 



3.1.4.3. 



Family 2. Isoteninidae Ameghino. 

 Teeth in compact rows and gradually passing from one form to the 



Cheek teeth moderately 



3.1.4.3. 



next, only the upper canine becomes enlarged at times. 



hypsodont ; upper premolars and molars 



with several cusps and crests on the inner 



side of the ectoloph, and with crochets on 



the metaloph. Lower premolars and molars 



with a, very well-developed, compressed cusp 



on the inner end of the anterior crescent. 



Isotemnus Ameghino. Canine small, 

 upper premolar triangular, molar 

 oblong. Eocene ; Notostylops beds of 

 Patagonia. 



Fleurostylodon Ameghino (Figs. 309 A, 

 327). Tychostylops, Plexotemnus, Dialophus fio. 327. 



Ameghino, etc. Eocene of Patagonia. Pleurostymon UmnMs Ameghino Upper Eocene 



o '_ , _ o (Notostylops beds), Patagonia. A, Upper fourth 



Eochcuirjitherium Ameghino. Broad premolar and second and third molars. B, Corre- 



, 1 -r, r T-. , • sponding lower teeth. i/i. 



lower molars. Eocene 01 Patagonia. 



Trimerostephcmws Ameghino. Oligocene; Astraponotus beds. Lower 

 Miocene ; Pyrotherium beds. 



Pleurocoelodon, Lop/hocoelus Ameghino. Lower Miocene. Pyrotherium beds. 



3.1-0.4.3. 



Family 3. Leontiniidae Ameghino. 

 Upper P and lower I^ enlarged, canines small, sometimes lacking, 

 the premolars and molars intergrading, the upper molars somewhat longer than broad 



VOL. Ill R 



