404 ORNITHOLOGY. 



Form. — About the size of and resembling T. melanogastra, Gould. Bill 

 moderate or rather short ; wing long ; second quill longest ; tail 

 moderate, wide ; legs long, rather slender ; toes thick, flattened, < 

 fully webbed. 



Dimensions. — Total length (of skin), male, seven and one-fourth 

 inches ; wing six and a half inches ; tail three inches. " Extent of 

 wings fifteen and a half inches." (Peale.) 



Colors. — Male. Head, neck, breast, and entire upper parts, except 

 the upper tail-coverts, dark fuliginous, nearly black on the head above 

 and back, lighter on the breast. Upper tail-coverts white. Abdomen 

 and under tail-coverts, white, every feather having a longitudinal and 

 terminal line of dark fuliginous. Feathers of the throat white at base. 

 Greater inferior wing-coverts light ashy or nearly white. Tail-feathers 

 white on their inner webs for about half their length ; outer webs and 

 terminal half of both webs, dark fuliginous. "Bill and legs, including 

 the toe-membranes, blue-black, without spots ; irides dark brown." 

 (Peale.) 



Hab. — Pacific Ocean. Island of Upolu. 



This species, of which but a single specimen is in the collection of 

 the Expedition, considerably resembles Thalasaidroma melanogastra, 

 Gould, B. of Australia, VII, PI, LXII, the only material difference 

 being, that the present bird has each of the white feathers of the abdo- 

 men and under tail-coverts marked with a dark fuliginous line, instead 

 of having a longitudinal band on the abdomen, as in the species men- 

 tioned. It is also apparently a shade darker in color ; the tibiae and 

 tarsi are more robust, and the toes strong and flattened. 



The specimen now before us has not the appearance of a young 

 bird ; and the species, so far as we can judge from a single individual, 

 is quite distinct, and, as such, we accordingly give it, but without 

 meaning to imply that we have fully investigated either the validity 

 of the species of this genus or the extraordinary complexity and appa- 

 rent confusion which evidently prevail in their synonymy. This bird 

 is, however, very probably, a species restricted to the Southern Pacific 

 Ocean, and hitherto unknown to naturalists. 



Of this bird, unfortunately, we find little recorded by either of the 

 naturalists of the Expedition. Mr. Peale only observes : 



