Birds of the Islands of the Coast of Yucatan. 241 



tional Museum^ 1886, p. 392). In tlie first place, Sitta 

 amurensis is only a snbspecific form of S. Ccesia, with which 

 it completely intergrades ; and in the second place, Sitta 

 clara is only one of an infinite number of intermediate forms 

 between Sitta ccesia and Sitta alhifrons. All these and other 

 snbspecific forms of Sitta casta have, Dr. Stejneger's asser- 

 tion to the contrary notwithstanding, a distinct chestnut patch 

 on the flanks ; and the only difference between examples of 

 the Nuthatch from Yesso and the valley of the Yenesay is 

 that the latter, when adult, are without the slight creamy 

 buff on the flanks. They can only be described as Sitta ccesia 

 aJbifrons, merely diflering from the extreme binomial form 

 in having the forehead without white, and a slight shade of 

 buff" on the flanks. It seems to me that the only way to 

 keep trinomials within bounds is to restrict them to the 

 extreme forms. 



XXII. — A List of the Birds of the Islands of the Coast of 

 Yucatan and of the Bay of Honduras. By Osbert Salvin, 

 M.A., F.R.S., &c. 



During the last two years Mr. G. F. Gaumer, a gentleman 

 well known for his zoological labours in Northern Yucatan, 

 at the instigation of Mr. Godman and myself, has made 

 several short visits to the islands off" the coast of Yucatan, 

 and spent a longer period on the Bay Islands, for the purpose 

 of collecting, chiefly, the birds of those somewhat remote 

 places. The islands visited were Meco and Holbox, off" the 

 northern coast of Yucatan, Mugeres Island, on the eastern 

 coast near Cape Catoche ; Cozumel Island, further south ; 

 and Ruatan Island and Bonacca Island, of the Bay-Island 

 group, off' the northern coast of the Republic of Honduras. 



The birds obtained during these expeditions I propose to 

 enumerate in the following paper, and to give at the end a 

 summary bearing on the distribution of the birds of this 

 portion of the American fauna. 



It will be seen from what follows that a large number of 

 species mentioned belong to the migratory birds which pass 



