THE NEARCTIC REGION. 329 



assuredly have left more numerous and widespread 

 indications of the former connections of these distant 

 lands than actually exist. And when we go back to 

 the Eocene period we are met by the interesting dis- 

 covery of an undoubtedly Lemurine animal in France, 

 and what are supposed to be allied forms in North 

 America. This proof of the great antiquity and wide 

 range of lemurs is quite in accordance with their low 

 grade of development ; while the extreme isolation and 

 specialization of many of the existing types (of which 

 the Aye-aye of Madagascar is a wonderful example), 

 and their scattered distribution over a wide tropical 

 area, all suggest the idea that these are but the rem- 

 nants of a once extensive and widely distributed group 

 of animals, which, in competition with higher forms, 

 have preserved themselves either by their solitary and 

 nocturnal habits, or by restriction to ancient islands, 

 like Madagascar, where the struggle for existence has 

 been less severe. Lemuria, therefore, may be discarded 

 as one of those temporary hypotheses which are useful 

 for drawing attention to a group of anomalous facts, 

 but which fuller knowledge shows to be unnecessary. 



Regions of the New World. We will now pass across 

 the Atlantic to the "Western Hemisphere, and consider 

 first the Nearctic region, or temperate North America, 

 whose present and past zoological relations with the rest 

 of the world are of exceeding interest. 



If we omit such animals as the musk-sheep (Ovibos), 

 which is purely Arctic, and the peccaries (Dicotyles), 

 which are hardly less distinctly tropical, the land- 



