104 Recently published Ornithological Works. 



3. Ridgivay on the genus Leucosticte. 



[Sexual, Individual, and Geographical Variation in the Genus Leuco- 

 sticte. By R. Ridgway. Field and Forest, ii. Sept. 1876.] 



Quantity of sijecimens we should have thought would at 

 least have tended to produce unanimity of opinion as regards 

 the sj^ecilic value of obscure species of birds. But that this 

 is not always the case is shown by the diverse views held by 

 Mr. Ridgway and Mr. J. A. Allen upon the subject of the 

 specific distinctions of the members of the genus Leucosticte, 

 specimens of which by the* hundred have been examined by 

 both disputants. Though the species of Leucosticte are not 

 unrepresented in our collections, thanks to the generosity of 

 our American friends^ we have not sufficient materials in this 

 country to form an independent opinion on so delicate a point 

 as to whether certain forms possess well-defined sexual 

 differences or not. Mr. Ridgway seems to have gone very 

 thoroughly into the subject; and so also has Mr. Allen ; and 

 we have no doubt the truth will be threshed out between 

 them. 



4. Ridgway on the Birds of Guadalupe Island. 



[The Birds of G uadalupe Island discussed with reference to the present 

 Genesis of Species. By R. Ridgway. Extracted from the Bull, of the 

 Nuttall Oru. Club, ii. July 1877.] 



This is an interesting paper inspired by a further con- 

 sideration of the birds inhabiting the little island of Guadalupe, 

 which lies off the coast of California. A visit to it by 

 Dr. E. Palmier a short time ago brought to light a curious 

 series m. facts relating to its fauna and flora, the birds being 

 found, though generically the same, to be all specifically 

 different from their continental allies. Mr. Ridgway now 

 examines the avifauna, after the plan adopted by Salvin in 

 his recent memoir on the birds of the Galapagos Islands 

 (Trans. Z. S. ix. p. 447 et seqq.), and comes to the conclusion 

 that the immigration and differentiation of species in 

 Guadalupe Island have been substantially the same as in the 

 Galapagos archipelago, but that the process of change, either 

 through shortness of time or slowness of operation, has not 



