CHAP. VII.] :\LUniALIA OF THE NEW WORLD. IT-S 



tropical climate, and would thus aiTord an ample area for tlie 

 continued existence and development of the typical Soutli 

 American fauna ; even had glaciers descended in places so low 

 as what is now the level of the sen, which, however, there is no 

 reason to believe tliey ever did. It is probable too, tliat this 

 low tract, which all round the Gulf of Mexico would be of con- 

 siderable width, offered that passage for interniigration between 

 North and South America, which led to the sudden appearance 

 in the former country in l*ost-Pliocene times, of the huge Mega- 

 theroids from the latter ; a migration ■\\ Inch took place in op- 

 posite directions as we shall presently show. 



The hirth-placc and mi'tjirdious of some mamraalian families 

 and genera. — We have now to consider a few of those cases 

 in which the evidence already at our command, is sufficiently 

 definite and comph-te, to enable us to pronounce with some con- 

 fidence as to the last movements of seA^eral important gioups of 

 manmialia. 



Pfimates. — The oci'urrence in Xortli America of numerous 

 forms of Lemuroidea, forming two extinct families, wliich are 

 believed by American palaeontologists to present generalized 

 features of both Lemuridce and Ilapalidse, while in Europe only 

 Lemurine forms allied to those of Africa have occurred in 

 deposits of the same age (Eocene), renders it possible that the 

 Primates may have originated in America, and sent one branch 

 to South America to form the Hapalida? and Cebidas, and 

 another to the Old World, giving rise to the lenuirs and true 

 apes. But the fact that apes of a high degree of organization 

 occur in the European Miocene, while in the Eocene, a monkey 

 believed to have relations to the Lemuroids and CebidcTe has also 

 been discovered, make it more probable that the ancestral forms 

 of this order originated in the Old World at a still earlier period. 

 The absence of any early tertiary remains from the tropical parts 

 of the two hemispheres, renders it impossible to arrive at any 

 definite conclusions as to the origin of groups which were, no 

 doubt, always best developed in tropical regions. 



Cetrnivora. — This is a very ancient and wide-spread group, the 

 families and trenera of which had an extensive ranjie in verv 



