298 ORIGIN OF LIFE IN AMERICA 



variety, produced by the new and peculiar climate, food and 

 soil to which it has been subjected." Hence Darwin * con- 

 sidered the rat as imported by man, and he adds that the 

 transportation of the mouse in a vessel from the mainland 

 is not improbable. 



Dr. Wallace concurs with Mr. Darwin in the belief that the 

 Galapagos islands agree with all other oceanic islands in so 

 far as they are devoid of indigenous mammals. He acknow- 

 ledges that the mouse, which had since been found to belong 

 ' to the American genus Hesperomys, differs somewhat from 

 other known species. Yet he remarks that we can scarcely 

 consider the species to be indigenous, firstly because these 

 creatures have been little studied in South America, and that 

 there may still be many undescribed mice there, and in the 

 second place because even had it been introduced by some 

 European or native vessel, there would have been ample time 

 in two or three hundred years for the very different conditions 

 to have established a marked diversity in the characters of the 

 species. Dr. Wallace f reiterates in conclusion Darwin's 

 statement that the islands are really destitute of truly in- 

 digenous mammals. 



Now since these great naturalists wrote about the Gala- 

 pagos archipelago, and stated their opinions on the mam- 

 malian fauna of the islands, the latter have been visited by 

 many competent observers, who brought their collections 

 home for careful study. Thus the mammals collected by 

 Dr. Baur on the islands were described by Dr. Allen, who 

 recognised among them a typical brown rat (Mus decu- 

 manus). He also thought that a skeleton which was picked 

 up on South Albemarle belonged to the black rat (Mus rattus). 

 There was likewise a bat which he identified as closely allied 

 to a Chilean form, but sufficiently distinct to deserve the 

 separate name of Atalapha brachyotis. Dr. Allen, J moreover, 

 points out that the Galapagos mouse does not belong to the 

 Old World genus " Mus " nor to " Hesperomys," but agrees 

 with Oryzomys, the well-known American rice-rats. Besides 



* Darwin, C., " Journal of Researches," p. 275. 



t Wallace, A. E., "Island Life," p. 278. 



t Allen, J. A., " Mammals from the Galapagos Islands." 



