378 GALAPAGOS AKCHIPELAGO. [chap. xvii. 



height crowned with its crater, and the boundaries of most of 

 the lava-streams still distinct, we are led to believe that within a 

 period, geologically recent, the unbroken ocean was here spread 

 out. Hence, both in space and time, we seem to be brought 

 somewhat near to that great fact that mystery of mysteries 

 the first appearance of new beings on this earth. 



Of terrestrial mammals, there is only one which must be con- 

 sidered as indigenous, namely, a mouse (Mus Galapagoensis), and 

 this is confined, as far as I could ascertain, to Chatham island, the 

 most easterly island of the group. It belongs, as I am informed 

 by Mr. Waterhouse, to a division of the family of mice charac- 

 teristic of America. At James island, there is a rat sufficiently 

 distinct from the common kind to have been named and described 

 by Mr. Waterhouse ; but as it belongs to the old-world division 

 of the family, and as this island has been frequented by ships for 

 the last hundred and fifty years, I can hardly doubt that this rat 

 is merely a variety, produced by the new and peculiar climate, 

 food, and soil, to which it has been subjected. Although no one 

 has a right to speculate without distinct facts, yet even with 

 respect to the Chatham island mouse, it should be borne in mind, 

 that it may possibly be an American species imported here ; for 

 I have seen, in a most unfrequented part of the Pampas, a native 

 mouse living in the roof of a newly-built hovel, and therefore its 

 transportation in a vessel is not improbable : analogous facts 

 have been observed by Dr. Richardson in North America. 



Of land-birds I obtained twenty -six kinds, all peculiar to the 

 group and found nowhere else, with the exception of one lark- 

 like finch from North America (Dolichonyx oryzivorus), which 

 ranges on that continent as far north as 54, and generally fre- 

 quents marshes. The other twenty-five birds consist, firstly, 

 of a hawk, curiously intermediate in structure between a Buzzard 

 and the American group of carrion-feeding Polybori ; and with 

 these latter birds it agrees most closely in every habit and even 

 tone of voice. Secondly, there are two owls, representing the 

 short-eared and white barn-owls of Europe. Thirdly, a wren, 

 three tyrant fly-catchers (two of them species of Pyrocephalus, 

 one or both of which would be ranked by some ornithologists 

 as only varieties), and a dove all analogous to, but distinct 

 from, American species. Fourthly, a swallow, which though 



