DISTRIBUTION 37 I 



ruption of local life may have caused." (Scudder.) Probably 

 many species were exterminated and many others became 

 greatly modified, though little is known as to the relationship 

 of the present fauna to the preglacial fauna. ' The glacial 

 cold still lingers over the northern part of this continent and 

 our present animals are only a remnant of the rich fauna that 

 existed in former ages, when the magnolia and the sassafras 

 thrived in Greenland." 



Island Faunae. The ability of insects to surmount barriers, 

 under favorable circumstances, is strikingly shown in the col- 

 onization of oceanic islands. Not a few insects, including 

 Vanessa cardui, have found their way to the isolated island 

 of St. Helena. In the Madeira Islands, according to Wollas- 

 ton, there are 580 species of Coleoptera, of which 314 are 

 known to occur in Europe, while all the rest are closely allied 

 to European forms. Subtracting 120 species as having been 

 introduced probably or possibly through the agency of man, 

 there remain 194 that have been introduced by " natural " 

 means. The rest, 266 species, are endemic, though akin to 

 European species. 



The scanty insect fauna of the Galapagos Islands includes 

 t\venty species of Orthoptera, which have been studied by 

 Scudder and by Snodgrass. Five of these are cosmopolitan 

 cockroaches, doubtless introduced commercially, and the re- 

 maining fifteen are all " distinctly South and Central American 

 in their affinities." Three of these fifteen are strong-winged 

 species which doubtless arrived by flight from the neighboring 

 mainland; indeed, Scudder records a Schist ocerca (S. exsul) 

 as having been taken at sea two hundred miles off the west 

 coast of South America, or nearly half way to the Galapagos 

 Islands. Thirteen of the fifteen are endemic, and five are 

 apterous or subapterous, while a sixth has an apterous female. 

 Apterous insects, noticeably common on wind-swept oceanic 

 islands, may have been carried thither on driftwood, though 

 it U more likely that the apterous condition arose on the 

 islands, where the better-winged and more venturesome indi- 



