VERTEBRATE LIFE IN AMERICA. 689 



allied genus is Dinictis, and several smaller cats are known from 

 about the same horizon. The Canidce are represented by Amphicyon, 

 a European genus, and by several species of Canis, or a very nearly 

 allied form. The peculiar genus Hycenodon, found also in Europe, 

 and the type of a distinct family, is abundant in the Miocene east of 

 the Rocky Mountains, but has not yet been found on the Pacific 

 coast. In the Pliocene of both regions the Canidce are numerous, 

 and all apparently belong to the existing genus Canis. The genus 

 Machairodus is still the dominant form of the cats, which are abun- 

 dant, and for the most part belong to the genus Felis. The extinct 

 Leptarctus is supposed to belong to the ZTrsidce, 1 and, if so, is the 

 oldest American representative of this family. In the Post-Pliocene, 

 the extinct Felidce include species nearly as large as a lion, and 

 smaller forms very similar to those still living. Bears, raccoons, 

 and weasels, have also been found. 



In the Pliocene of South America, Machairodus represents the 

 Felidce, while the genera Arctotherium and LTycenarctus belong to the 

 Bear family. Species of. Mustela and Canis have also been found. 

 In the caves of Brazil, the fauna of which is regarded as Post-Plio- 

 cene, one species of Machairodus is known, and one of Syncelurus. 

 Canis and Lcticyon, still living in Brazil, and the extinct genus Speo- 

 thos, represent the Canidce. Mephitis and Galictis, among the wea- 

 sels, were also present, and with them species of JVasua and Arctothe- 

 rium. 



We come now to the highest group of Mammals, the Primates, 

 which includes the Lemurs, the Apes, and Man. This order has a 

 great antiquity, and even at the base of the Eocene we find it repre- 

 sented by several genera belonging to the lower forms of the group. 

 In considering these interesting fossils, it is important to have in 

 mind that the Lemurs, which are usually regarded as Primates, 

 although at the bottom of the scale, are found at the present day only 

 in Madagascar and the adjacent regions of the globe. All the Ameri- 

 can monkeys, moreover, belong to one group, much above the 

 Lemurs, while the Old World apes are higher still, and most nearly 

 approach man. 



In the lower Eocene of New Mexico we find a few representatives 

 of the earliest known Primates, and among them are the genera 

 Lemuravus and Limnotherium, each the type of a distinct family. 

 These genera became very abundant in the middle Eocene of the 

 West, and with them are found many others all, however, included 

 in the two families Lemuravidce and Limnotheridce. Lemuravus 

 appears to have been most nearly allied to the Lemurs, and is the 

 most generalized form of the Primates yet discovered. It had forty- 

 four teeth, forming a continuous series above and below. The brain 



1 Ursidce, the family including the bears, raccoons, etc. 

 vol. xii. 44 



