238 Naturalist at Large 



Europe and enlarged them — that is, turned them loose — 

 and in no time they became enormously abundant again. 



Few laymen know that the camels originated in America 

 and went through most of their evolutionary history in 

 what is now the western part of the United States. During 

 the height of the glacial period enough oceanic water was 

 tied up in the gigantic polar icecap to lower the level of 

 the oceans, so that many land areas now separated by 

 water were then connected. Thus the camels reached the 

 Old World and the elephants reached the New; and 

 strangely enough, according to a Russian scholar, Nazo- 

 noif by name, the sheep not only passed from Asia to 

 North America but went back again, leaving the ancestors 

 of all our various species of bighorn behind them. 



Geologically speaking, a fairly recent uplift of land 

 formed Central America (for the Caribbean Sea was once 

 a bay of the Pacific) and allowed camels to reach South 

 America, where they persist as the llama, alpaca, guanaco, 

 and vicuiia. The stock then died out in North America. 

 The elephants pushed down as far as Ecuador and likewise 

 disappeared, as they did all over North America, where 

 they once existed in countless numbers of individuals and 

 a great variety of species. 



I can hear my reader ask, "How do you know that the 

 Caribbean was once a bay of the Pacific?" The answer was 

 given by Alexander Agassiz during his explorations with 

 the steamship Blake. He found that there was a greater 

 difference between the deep-water fauna on the inside and 

 that on the outside of the arc of Lesser Antillean islands 

 than there was between the fauna inside the arc and that 

 on the Pacific side of the Isthmus of Panama. Only last 



