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,$ 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. It., “Island Life,” p. 278. 
f Allen, J. A., “ Mammals from the Galapagos Islands.” 
