320 tiecently published Ornithologicul Harks. [Ibis, 



32,800 birds listed in a census made in 1916, some 31,200 

 have their homes and breeding-grounds. 



Far the most numerous in individuals are the Sootj' Tern 

 (Sterna fuscatu) and the Noddy [Anous stolidus) ; others of 

 less importance as regards numbers are the Least Tern 

 {Sterna a. untillarum) , the Roseate (S. dougalU), the Man- 

 o^-War Bird {Fie<iata iiiagnijicens rothschildi), and the 

 Boobies (Su/a leucoynstris and S. sula), but the last three 

 do not nest. 



Good accounts of all these species are given by 

 Dr. Bartsch in the present paper, which is illustrated 

 bv a large number of pliotographs. There is also an 

 interesting list of all the birds which have been recorded 

 from the islands, as well as of the land-birds which have 

 been observed there on different occasions on migration. 



Chapman on variation in Ostinops decumaiius. 



[Uuusuil types of apparent li-eograpliic variation in colour and of 

 individual variation in size exhibited by Oslinops clecumanus. By Frank 

 M. Chapman. Proc. Biol. Soc. Washington, vol. xxxiii. 1920, pp. 25-32.] 



Mr. Chapman has recently examined a large series of 

 examples of Ostinops decumanus, chiefly from southern Peru 

 and Bolivia, and also from Matto Grosso in south-west 

 Brazil, and he finds among these birds, both male and 

 female, a remarkable phenomenon of a varying number of 

 feathers of the body and wing-coverts being wholly or in 

 part yellow or more rarely white. Such a variation, if 

 found in a single individual, would certainly be considered 

 as pathological albinism or xanihochroism. But this curious 

 variation is found to a variable extent in so large a propor- 

 tion of the birds examined tiiat it mnst be considered a 

 diagnostic character, and to draw attention to it Mr. Chapman 

 proposes to distinguish this form as a distinct subspecies, 

 Ostinops decimianus maculosus. In birds from north of the 

 Amazon valley this variation does not occur. 



In regard to size, Mr. Chapman finds a very remark- 

 able variation among the males only — both those from 

 the northern and southern parts of South America. 



