a:merican and west ixdian fauna and flora. 121 



admirably traced by Alph. ]\Iiine-Ed wards, in an interesting 

 memoir on the fauna of the antarctic regions. He calls at- 

 tention to the effect upon the distribution of penguins of 

 icebergs carried by currents. These birds are excellent swim- 

 mers, and fond of resting on floating ice ; they are prepared 

 for long voyages, and thus may have been transplanted from a 

 single centre to the varied locaHties where they are now found. 

 In their search for food they must naturally migrate to great 

 distances durins" the lono- antarctic winters, when they cannot 

 carry on their usual fishing avocations. The path of the ice- 

 bergs, as dependent on currents, may even enable us to trace 

 the orio-inal peno-uin home. Milne-Edwards concludes that the 

 inhospitable country of Victoria was the origin of the most char- 

 acteristic animals of the antarctic region. 



It will be quite possible, when sufficient material has been col- 

 lected, to map out the course of the pelagic fauna ; and from its 

 bottom distribution much light will be thrown on the course of 

 the currents. Thus the existence at Newport of Agalma, Clio, 

 and Pneumodermon, — inhabitants of arctic seas, Labrador, 

 Maine, and northern New England, — is direct evidence that 

 the cold arctic current finds its way round Cape Cod to the 

 opening of Narragansett Bay. In the same way we may trace 

 the northern course of the Gulf Stream by the presence of Sar- 

 gassum, Porpita, Leptocephali, and southern pteropods, etc., 

 which are carried each year to the coast of southern New Eng- 

 land. The range of southern globigerinse and pteropods will 

 fix the eastern limits of the Gulf Stream, as northern types 

 determine those of the cold current along the east coast of the 

 United States. 



It is most hazardous, especially on insufficient data, to spec- 

 ulate upon former land connections ; and yet, in many cases, 

 the presence of identical genera of mammals seems to leave us 

 no alternative. When, however, there are powerful currents 

 running through the narrow channels that separate adjoining 

 islands, or when these currents skirt the shores of island ranges 

 and of neighboring continents, it is not always necessary to 

 assume such an extinct continental connection. The careful 

 study of the distribution of mammals on the islands of the 



