408 Annals of the Carnegie Museum. 



upon the American Ornithologists' Union Code. Under each species 

 the number of specimens in the collection is specified, with the 

 several localities represented. All measurements are in millimeters. 

 I. Colymbus dominicus dominicus Linnaeus. 



Five specimens: Great Inagua (Mathewtown) ; Watlings Island. 



Only two adult specimens are included, one from each locality, 

 and both females. They measure as follows : wing, 90 and 92 ; culmen, 

 22 and 20. After having critically studied the series upon which 

 Colymbus dominicus brachypterus Chapman was based, as well as 

 additional material from Costa Rica and Jamaica, I am strongly 

 inclined to doubt the validity of the subspecies in question. The 

 supposed color-characters fail to hold good; while the difference in 

 size seems too slight and inconstant to alone justify subspecific 

 separation. Averages are as follows: 



Wing. Culmen. 



Two males from Cuba 97 25.5 



Two females from Cuba 94 21 



Two females from the Bahamas 91 21 



Eight males from Texas 87.5 22 



Five females from Texas 84.3 19 



Three males from Costa Rica 94 25 



One female from Costa Rica 94 21 



There is thus an obvious sexual difference in size, which must be 

 taken into account in making comparisons. Examples from Costa 

 Rica approach typical dominicus so closely that if brachypterus be 

 deemed worthy of recognition at all it will be necessary to restrict 

 the name to the birds from Texas and Mexico. Compare also, in 

 this connection, the measurements given by Mr. Cory {Birds Ba- 

 hama Islands, 1890, 222) for the Bahaman bird, as well as Messrs. 

 Salvin and Godman's remarks on the same subject {Biologia Centrali- 

 Americana, Aves, III, 1904, 443). 



Both adults are in full breeding dress, with dark throats, although 

 Mr. Ogilvie-Grant {Catalogue Birds British Museum, XXVI, 1898, 

 521) says that "the black throat begins to appear early in May" 

 (italics mine). "Iris bright orange yellow, bill black, tip white; 

 tarsi and toes black above, plumbeous below." 



Three birds from Watlings Island, March 12, have already attained 

 the Juvenal dress, and are fully as large as adults. In these the crown 

 is dusky, with some white mottling, obsoletely indicating median 

 and lateral stripes; the sides of the head, however, are mottled in- 



