376 BUBEAU OF AMEEICAN ETHNOLOGY [bull. 52 



it is contrasted except in the bear; the exact curves of the troclilear 

 ridges, particularly of the external one, also approximate most closely 

 to those of the bear. 



The thickness of the shaft at the lowest portion of the diaphysis is 

 relatively to its breadth much greater in the TetraprotJiomo than in 

 either man or any other primate, being precise^ like that observed 

 in many feline species. 



Finally, the popliteal surface in the Monte Hermoso femur is per- 

 ceptibly convex from side to side. In man and the majority of apes, 

 it is slightly concave or fiat, in the gibbon and some monkeys slightly 

 convex, in the dogs slightly concave to slightly convex, in the cats 

 flat to convex (ocelot, Hoplophoneus) , as in the Tetraprothomo. 



Conclusions. — The femur of the Tetraprothomo bears only a slight 

 resemblance to that of man or the anthropoid apes, and but little 

 greater to that of the lower monkeys. It presents no feature which 

 would make obligatory or even possible its inclusion in the Primate 

 class, but on the other hand it shows many features which approx- 

 imate it to a distant family of mammals. 



The class of mammals with which the characteristics of the femur 

 connect it most closely are the carnivores, and among these especially 

 the cats. All the evidence leads to the deduction that the Monte 

 Hermoso femur is a femur of some extinct moderate-sized felid, 

 though possibly a member of a subfamily other than that of the 

 felines. It is probably useless to look for an exactly analogous form 

 among the present South American or other modern cats^ and this 

 statement may apply even to the North American fossil Felidse, but 

 that does not affect its claim as a member of the same stem. 



That Carnivora have not been found hitherto among the Monte 

 Hermoso fauna does not prove their absence from the formation, for 

 as yet tliis is known but very imperfectly; moreover, while looking over 

 the Monte Hermoso fossils in the Museo de la Plata with Professor 

 Roth, the writer came across the metatarsal of a large-sized carnivore, 

 so that even the claim of the absence of this class of mammals from 

 the Monte Hermosean deposit is no longer tenable. 



Comparison with fossil Carnivora. — In order to make the identifica- 

 tion of the Monte Hermoso femur still more definite, the writer 

 examined, with the kind assistance of Mr. J. W. Gidley and Dr. W. D. 

 Matthew, the femora of fossil dogs and cats present in the paleonto- 

 logic collections of the United States National Museum and the 

 American Museum of Natural History. The comparison was carried 

 out especially with the Felidse Hoplophoneus (Oligocene) , Nimraous 

 (Oligocene) , Dinictis (Oligocene) , and Pogonodon (Miocene) ; with the 

 Canidse Daphsenus (Oligocene), jElurodon (Miocene), Enliydrocyon 

 (Miocene), and Mesocyon (Oligocene); and with the procyonid 

 Phlaocyon (Miocene). All of these are North American forms, no 

 South American fossils being available in the two institutions. 



