Tertiary Vertebraia of the West. 



519 



tooth has no anterior lobe, and the inferior tooth has no internal 

 tubercle, but the heel is present. Nimravus is known from two 

 species nearly allied to Archcelurus, but distinguished by wanting the 

 anterior premolars in both jaws, while the large canine in the upper 

 jaw is denticulated. In dental foi'mula and characters, it resembles 

 Hoplophoneus, with the addition of a tubercular inferior molar tooth 

 There is no evidence to show the length of the body. The canine 

 teeth were probably exposed ; and, as penetrating weapons, are un- 

 rivalled among carnivorous animals. Three species of Dinictis are 

 described ; it is a primitive sabre-tooth genus, closely connected with 

 the false sabre-toothed group. The superior canine is long and com- 

 pressed, and rests against an inferior marginal flange of the mandible, 

 whose surface is divided from that of the symphysis by a strong 

 angle. Pogonodon connects Dinictis with the higher sabre-toothed 

 genera, but wants the tubercular lower molar of Dinictis, while it 

 possesses the second inferior premolar which is wanting in Hoplo- 

 phoneus. The species are the largest of the North American sabre- 

 tooths. 



platycopis. 



P. platycopis is equal to the largest Drepanodon, and only inferior 

 in size to Smilodon. The skull is equal in size to the largest Brazilian 

 variety of the Jaguar. The molar teeth are rather small, the second 

 sectorial is primitive, and peculiar in its robust heel. Moplophoneus 

 is a genus with the dental formula of Drepanodon and the true Cats, 

 but which retains the primitive form of the sectorial teeth in the 

 lower jaw. The type-species was as large as the Canadian Lynx, 

 with long and slender upper canines. Three species are described. 

 Here Book i. terminates, leaving the remainder of the John Day 

 fauna, as well as that of the Pliocene period, for description in the 

 second book of volume iii. The beautiful plates by which the text 

 is illustrated reflect credit upon the artists, as well as upon the 



