58 BULLETIN OF THE NUTTALL 



measurements taken by Mr. Allen. As he informs me, however, 

 that the variation in this respect is very small, it is probable the 

 average would be little changed by their addition. 



In bestowing the specific name, I have paid but a deserved com- 

 pliment to the zeal and enthusiasm of Mr. C. A. Allen, but for 

 whose efforts in obtaining the specimens necessary for comparison, 

 and careful field-notes, the species might have remained for a long 

 time still unrecognized. 



THE BIRDS OF GUADALUPE ISLAND, DISCUSSED WITH 

 REFERENCE TO THE PRESENT GENESIS OF SPECIES. 



BY ROBERT RIDGWAY. 



The importance of insular faunae in their bearing on ^the sub- 

 ject of the derivation of species, has been recognized by eminent 

 writers ; and certain islands, remote from the mainland, among 

 which may be mentioned the Galapagos, have received marked 

 attention. An excellent memoiu upon the birds of the latter group 

 has lately been published by Mr. Osbert Salvin,* who discusses the 

 relationship of certain peculiar forms to their continental allies, 

 and even goes so far as to point out among the latter the present 

 representatives of the parent stocks from which the genera now 

 peculiar to the Galapagos have been derived. That Mr. Salvin is 

 probably correct in his conclusions, is very strongly indicated by 

 certain facts developed from a study of the fauna of Guadalupe, 

 where in the case of almost every species, precisely the same local 

 modifications ai-e observable ; the process of change in the latter 

 case, howevei*, has been either more recent or more gradual, since 

 close affinity to continental representatives is clearly seen in every 

 species, the extreme diff'erentiation met with in the Galapagos types 

 not having yet been reached.t 



* On the Avifauna of the Galapagos Archipelago. By Osbert Salvin, M. A., 

 F. R. S., etc. Transactions of the Zoiilogical Society of London, Vol. IX, 

 Part IX, pp. 447-510, pis. Lxxxiv - Ixxxix. May, 1876. 



+ These modifications seem to be, (1) enlargement, or elongation, of the bill 

 and feet, (2) abbreviation of the wings and tail, and (3) darkening of the colors 



