242 Mr. O. Salvin on the Birds of the 



and repass in spring and autumn between North America 

 and their winter-quarters ; and it is evident, from their num- 

 berSj that this line of coast, stretching, as much of it does, 

 north and south, forms one of the lines of migration of such 

 birds, and that the islands serve as so many resting-places 

 in their journey. This part of the subject I propose to treat 

 in more detail at the end of this paper, and also to examine 

 the more difficult question involved in the relationship of the 

 resident birds to those of the mainland and the Antilles. 



Mr. Gaumer has now returned to his old quarters in 

 Yucatan, where we hope that he will still find time to carry 

 on the investigations he has hitherto pursued so successfully. 



Of the islands visited, Cozumel alone had previously 

 been examined, and the following papers refer to its bird- 

 fauna : — 



1. Description of some new Species of Birds from Co- 

 zumel Island, Yucatan. By Robert Ridgway. '^Author's 

 edition.^' Extracted from the Proc. Biol. Soc. Washington, 

 iii., and distributed by Mr. Eidgway, 2nd March, 1885. 



2. On a Collection of Birds from the Island of Cozumel. 

 By Osbert Salvin. Ibis, April, 1885, pp. 185 et seqq. 



3. ('atalogue of a Collection of Birds made on the Island 

 of Cozumel, Yucatan, by the Naturalists of the U.S. Fish- 

 Commission Steamer 'Albatross/ Capt. Z. L. Tanner, Com- 

 mander. By Robert Ridgway. Proc. U.S. Nat. Mus. viii. 

 pp. 560 et seq. (Sept. & Oct. 1885). 



As the first of these papers only contains short preliminary 

 descriptions, which are all given at greater length in the 

 third, I have not thought it necessary to quote it ; but to 

 make the present paper complete as far as it goes, the others 

 are referred to where required. 



/ -^ 1. TURDUS MUSTELINUS. 



Tardus mustelinus, Gm. ; Salv. & Godm. Biol. Centr.- 

 Am., Aves, i. p. 9, 



Mugeres I. ; Cozumel I. 



A migratory species from the north, and common in Co- 

 zumel Island. It has not been noticed in Northern Yucatan, 



