456 Mr. J. H. Gurney on some Raptores. 



was described by Mr. Ridgway in vol. iii. of the ' Land-Birds 

 of North America/ pp. 208, 209, under the title of '' Rostrha- 

 mus sociabilis, var. plumbeus ; " and the Norwich Museum has 

 lately been indebted to the authorities of the Smithsonian 

 Institution, through the good offices of Mr. Ridgway, for two 

 Florida examples of this race. Both these are marked as 

 males, though, from the longer wing of one specimen, I am 

 inclined to think it may in reality be a female. This example 

 is very nearly adult ; the other is in change from immature to 

 adult plumage ; a third Florida specimen, lately supplied to 

 the Norwich Museum by Mr. Whitely, is entirely in imma- 

 ture dress. On comparing these specimens with South- 

 American examples of R. sociabilis =^leucopygus [vide Ibis, 

 /. c.) , I find no difference, except in the somewhat larger 

 dimensions of the Florida bird. The following are mea- 

 surements of specimens in the collection of Messrs. Salvin 

 and Godman and in the Norwich Museum; amongst the 

 latter is an immature specimen from Peru of larger size than 

 than the other South- American examples, and with a more 

 developed upper mandible, which I suspect may belong to 

 an un described species. 



Rostrhamus sociabilis. 



Middle 



Wing. Tarsus. toe s. u. Oulmen «. c. 



in. in. in. in. 



Adult, Demerara, N. M 13-60 1-80 1-50 llO 



Immature, Brit. Guiana, coll. 



S.&G 14-15 1-90 1-70 1-15 



Ditto, ditto 13-30 1-80 1-70 1-15 



Adult, Brazil, N. M 13-30 2-00 1-50 1-10 



Immature, U. S. of Colombia, 



coll. S.&G. (marked?).. 13-90 1-90 1-75 1-25 



Adult, Bolivia, N. M 13-70 1-90 1-60 1-25 



Immature, Peru, N. M 14-20 1-90 170 1-40 



Rostrhamus plumbeus. 

 Immature, Florida, N.M. .. 14-00 1-80 1-50 1-25 



Ditto in change, Florida, 



marked c?,N.M 14-30 2-00 1-70 MO 



Nearly adult, Florida, marked 



J , N. M 14-90 2-00 1-70 MO 



