330 Recent Literature. Yy% 



volcanic, and Dr. G. Baur's theory that thev are the remnants of a 

 former large oceanic land area — and presents the evidence afforded by the 

 birds. He considers in this connection the relationships of the five 

 peculiar Galapagoan bird genera, and finds that only two " are of evident 

 American relationship. The remaining three have so obvious a leaning 

 toward certain Hawaiian Dic?eidine forms that the possibility of a former 

 land connection, either continuous or by means of intermediate islands 

 as ' stepping stones,' becomes a factor in the problem. It may be," he 

 adds, that the resemblance of these three genera to " Hawaiian forms is 

 merely a superficial one, and not indicative of real relationship. I do 

 not by any means claim, on the strength of such evidence, a common 

 origin for them, but merely present the facts as 'food for reflection.'" 



In this connection Mr. Ridgway gives a summarj' of the ranges of the 

 genera of Galapagoan birds, without, however, deriving from this study 

 any decisive evidence as to " whether the non-peculiar portion of the 

 Galapagoan avifauna is most nearly related to that of the adjacent main- 

 land of South America or that of lower Central America or the West 

 Indies." 



Mr. Ridgway comments on the perplexing difticulties that beset the 

 discrimination of the many closely related forms, and says that " when, 

 ever there seemed to be a well-defined average difference between speci- 

 mens from different islands, I have not hesitated to separate them as local 

 forms. No other course, indeed, was practicable; for were 'lumping' 

 once begun there could be no end to it, unless purely arbitrary limits 

 were given to the species recognized, and if followed to a logical conclu- 

 sion might easily end in the recognition of a single variable species, 

 equivalent in its limits to the genus." 



The distribution of the 105 species thus far recorded from the Galapagos 

 Archipelago is shown in a series of tables, as to the group of islands 

 collectively, and for each island individually. Then follows the detailed 

 treatment of the species, with charts showing their distribution in the 

 Galapagos Islands. It is interesting to observe that five-sixths (53 

 species) of the Passerine birds belong to four genera — Nesomiiniis, Cer- 

 thidea, Geospiza, and Camarhynchus — peculiar to the Galapagos, and 

 that half the remainder belong to the genus Pyrocephaliis ; and that all 

 but two of the 61 species of Passerine birds are peculiar to the Islands, 

 the other two being of casual occurrence. Most of the remainder are 

 wide-ranging water birds, with a few species peculiar to the Galapagoan 

 fauna. 



The species are treated exclusively from the systematic standpoint, 

 giving their synonymy and bibliography, with full descriptions, tables of 

 measurements, and their ranges, together with discussions of their relation- 

 ships. The paper concludes with a bibliography of all the works and 

 papers relating to Galapagoan ornithology. Mr. Ridgway has thus given 

 us a detailed and masterly monograph of the birds of the most interesting 

 and instructive group of islands known to science. — J. A. A. 



