690 THE POPULAR SCIENCE MONTHLY. 



was nearly smooth, and of moderate size. The skeleton most re- 

 sembles that of the Lemurs. A nearly allied genus, belonging to the 

 same family, is Hyopsodus. Limnotherium (Tomitherium) also is 

 nearly related to the Lemurs, but shows some affinities with the South 

 American marmosets. This genus had forty teeth. The brain was 

 nearly smooth, and the cerebellum large, and placed mainly behind 

 the cerebrum. The orbits are open behind, and the lachrymal fora- 

 men is outside the orbit. Other genera belonging to the Limno- 

 theridm are Notharctos, Hipposyus, Microsyops, Palceacodon,, Thino- 

 lestes, and Telmatolestes. Besides these, Antiacodon (Anaptomor- 

 phus), JBathrodon, and Mesacodon, should probably be placed in the 

 same group. In the Diplacodon beds, or upper Eocene, no remains 

 of Primates have yet been detected, although they will doubtless be 

 found there. All the Eocene Primates known from American strata 

 are low generalized forms, with characters in the teeth, skeleton, and 

 feet, that suggest relationships with the Carnivores, and even with the 

 Ungulates. These resemblances have led paleontologists to refer 

 some imperfect specimens to both these orders. 



In the Miocene lake-basins of the West, only a single species of 

 the Primates has been identified with certainty. This was found in 

 the Oreodon beds of Nebraska, and belongs to the genus Laopithecus, 

 apparently related both to the Limnotheridce and to some existing 

 South American monkeys. In the Pliocene and Post-Pliocene of 

 North America no remains of Primates have yet been found. 



In the Post-Pliocene deposits of the Brazilian caves, remains of 

 monkeys are numerous, and mainly belong to extinct species of Cal- 

 lithrix, Cebus, and Jacchus, all living South American genera. Only 

 one extinct genus, Protopithecus, which embraced animals of large 

 size, has been found in this peculiar fauna. 



It is a noteworthy fact, that no traces of any Anthropoid apes, or 

 indeed of any Old World monkeys, have yet been detected in America. 

 Man, however, the highest of the Primates, has left his bones and his 

 works from the arctic circle to Patagonia. Most of these specimens 

 are clearly Post-Tertiary, although there is considerable evidence 

 pointing to the existence of man in our Pliocene. All the remains yet 

 discovered belong to the well-marked genus Homo, and apparently 

 to a single species, at present represented by the American Indian. 



In this rapid review of mammalian life in America, from its first 

 known appearance in the Trias down to the present time, I have en- 

 deavored to state briefly the introduction and succession of the princi- 

 pal forms in each natural group. If time permitted, I might attempt 

 the more difficult task of trying to indicate what relations these vari- 

 ous groups may possibly bear to each other ; what connection the 

 ancient mammals of this continent have with the corresponding forms 

 of the Old World; and, most important of all, what real progress 



