1892.] NATURAL SCIENCES OF PHILADELPHIA. 147 



to it. The bill is much heavier than any of the specimens of 

 S. longicuudns, the plumage above is decidedly more sooty and the 

 tarsi are entirely uniform in color with the feet. The two species 

 are, however, very difficult to separate owing to the great amount 

 of individual variation which they exhibit. 



The specimen of S. parasiticus measures as follows: Wing 

 12-85 inches. Culmen 1-27 inches. Tail 8-05 inches. 



7. Stercorarius longicaudus Vieill. Long-tailed Jaeger. 



The specimens of Long-tailed Jaegers, all of which were collected 

 July 16 in Melville Bay, show great variation in plumage and no 

 two in the series of seven are exactly alike. All have the tarsi 

 blue-gray strongly contrasted with the black feet, though the light 

 color sometimes terminates above the small hind toe and sometimes 

 extends below it to the upper part of the foot. 



No. 26,909, (Acad. Coll.), female, appears to be most typical of 

 the adult bird. The plumage in this specimen is nowhere barred or 

 mottled; the throat and breast are pure white passing gradually 

 into slate gray about the middle of the abdomen, and this color 

 becomes darker on the under tail coverts. On the sides of the 

 breast the gray reaches forward to the shoulders, while the under 

 wing coverts are blackish slate. The back is slate gray, darker on 

 the wings ; the primaries and tail are black. 



In No. 26,905, female, the gray reaches farther up on the breast 

 and the central tail feathers are not so long. 



In No. 26,904, female, (du.sky phase ?) the whole lower surface is 

 suifused with sooty gray, though this color is not uniform, as there 

 are a considerable number of white feathers scattered over the 

 breast. The upper surface is mottled with slate-gray and dusky 

 feathers. The under tail coverts and flanks are transversely barred 

 with white but the under wing coverts are plain dark slate. 



No. 26,903, female, shows distinct traces of dark transverse bars 

 over the lower breast and abdomen, and has dark shaft lines to the 

 feathers of the throat. Most of the under tail coverts are barred 

 with white and the under wing coverts are barred and mottled. 



No. 26,907, male, is similar but has the breast pure white while 

 the barrings on the under wing and tail coverts, sides and flanks 

 are very distinct. The throat is very strongly marked wdth dusky 

 shaft stripes while many of the feathers of the back show trans- 

 verse bars of Avhite. 



