EXTINCT CATS. 287 



the last molar being small and oval. In the limbs the femur 

 has a third trochanter • the five-toed hind-feet were probably 

 plantigrade, and present considerable resemblances to those of 

 the primitive Civets and Dogs, while the claws were retractile. 

 The genus is exclusively North American, and is represented 

 by some three species from the Miocene strata of Nebraska, 

 Colorado, and Oregon, its typical member being Dinictis 

 felina, which appears to have been an animal of the approxi- 

 mate dimensions of a Lynx. 



Of D. cyclops Professor Cope remarks that " although of an 

 inferior position in the system of Carnivora, its powers of de- 

 struction must have excelled those of the Catamount [Lynx]. 

 While the skull is generally less robust, its sectorial teeth are 

 not smaller nor less effective than those of that animal, and the 

 canines far excel those of the living species, as instruments 

 for cutting their prey." 



VII. GENUS NIMRAVUS. 

 Nimravus, Cope, Proc. Acad. Philad. 1879, p. 169; id., Amer. 

 Naturalist, vol. xiv. p. 842 (1880). 

 Nearly allied to the last, this genus, which is likewise North 

 American, forms an exception to the present group in that 

 there are only two pairs of pre-molar teeth in the lower jaw. 

 In the upper jaw the first pre-molar is minute, and the molar 

 transversely elongated ; while in the lower jaw the carnassiaJ 

 tooth is devoid of an inner cusp, and the second molar very 

 small. The femur has no third trochanter. While the pre- 

 ceding genus is most common in the Lower Miocene White 

 River beds, the present one is confined to the overlying Upper 

 Miocene John Day beds of Oregon, where it is represented by 

 N. gomphodus and N. confertus, both of which may be compared 

 in size to a Leopard. In all the points in which the genus differs 

 from Dinictis y it approximates to the modern Cats : precisely 

 as might have been expected from the higher geological hori- 

 zon in which its remains occur. 



