Mr. R. B. Sharpens Catalogue of Accipitres. 337 



hitherto considered; and to one of these, the genus Ros- 

 trhamus^, I would now refer. 



The birds of this genus are especially characterized by a 

 bill of extraordinarily slender proportions, in which the hook 

 terminating the upper mandible is prolonged in a most re- 

 markable manner, forming an admirable tool for extracting 

 from their shells the freshwater mollusks on which these birds 

 in great measure subsist, whilst a similar slenderness of pro- 

 portion is observable in the long and sharp talons with which 

 their feet are armed. 



Messrs. Baird, Brewer, and Ridgwayf apply the specific 

 name of sociabilis (Vieillot, ex Azara) to the species which 

 Mr. Sharpe describes under the name of leucopygus proposed 

 for it by Spix; and in this, I think, they are right, as it 

 appears to me that both these names refer to the same spe- 

 cies, and '' sociabilis," beiug the older, of course has priority. 



The bird described by Azara, and from his descrij)tion rede- 

 scribed by Yieillot in the ' Nouveau Dictionnaire,^ vol. xviii. 

 p. 318, under the name of Herpetotheres sociabilis, was im- 

 mature, which would make it difficult to decide to which 

 species it should be referred, were it not for the fact that 

 Azara made his collections in the neighbourhood of the river 

 Parana, and that in this district of the province of Buenos 

 Ayres the R, leucopygus of Spix is known to occur. 



The late Mr. Durnford, writing in ' The Ibis ' for 1877 

 respecting the birds of Buenos Ayres, and especially as to 

 his collections in the neighbourhood of a branch of the 

 Parana, mentions this species, on page 188, as " resident and 

 not uncommon;'''' and an adult specimen procured by that 

 gentleman at Lujan-bridge, on the Campana railway, Buenos 

 Ayres, is now in the possession of Messrs. Salvin and GodmanJ. 



* The name is thus spelled in the original description of the genus in 

 Lesson's ' Traite/ p. 55 ; in Mr. Sharpe's volume the spelling adopted is 

 Rosthramus. 



t Vide ' Birds of North America/ vol. iii. p. 208. 



\ The following is copied from Mr. Diu'nford's ticket attached to ihis 

 specimen : — 



" <S . Iris rich crimson, cere orange, legs and feet darker orange ; stomach 

 full of water-moUusks," 



