72 



split up into three groups, the ^luroidea (Cats, etc.), the 

 Cynoidea (Dogs, etc.), and the Arctoidea (Bears, etc.). 

 Some of the extinct Caruivora shew transition forms between 

 these now distinct sections. The Pinnipedia have been 

 greatly modified in accordance with their aquatic habits. 

 They are most nearly allied to the Arctoid section of the 

 Fissipedia, and, notwithstanding the great modification, a 

 passage may be traced from the typical Seals (Phocidge) 

 through Trichechus (Walrus) and Otaria (Sea-Bear) to the 

 true Carnivora. 



Turning now to the important line leading- upwards to 

 the Primates, the highest Mammals, we find that soon after 

 diverging from the primitive Ccrnivora a side branch is 

 given off which leads outwards to the ProsimisB (Lemurs). 

 This group has not undergone much evolution, and as it 

 probably arose very far back, the existing members may be 

 taken as representing the early ancestral forms of the 

 Primates. A considerable gap exists, however, between the 

 Lemurs and the Primates as now known. Some fossil 

 Prosimiae show resemblances to the primitive Ungulates, but 

 such features may be merely characteristics inherited by both 

 groups from the generalised higher Mammal which was their 

 common ancestor. Certain North American fossil forms 

 are in some respects transitional from the Prosimias to the 

 Primates. Probably they represent the earlier and less 

 specialised Lemurs, or possibly the ancestral Primates from 

 which the Lemurs arose. Tarsms and Chiromys must be 

 regarded as forming divergent branches, while the rest of the 

 existing Prosimiae do not exhibit much modification. 



The Primates are shown in the table as forming five 

 more or less divergent branches from a main stem, viz., 

 the Arctopitheci (Hapalidae or Marmosets), the Platyrrhini 

 (Cebidse or American Monkeys), the Cynomorpha (Cercopi- 

 thecidse or Old -World Monkeys), the Anthropomorpha (Simi- 



