550 ORNITHOLOGY AND OOLUui. 



Description. 



Adult. — On the forehead is a triangular white spot extending to the eye ; crowu 

 occiput, and a line from the eye to the upper mandible, deep-black ; entire uppei 

 plumage and wings clear bluish-gray; first two primaries with the outer web and 

 half the inner next the shaft, grayish-black, ends of the same color, inner margins 

 white, the shafts of these two quills are black ; the other primaries same color as the 

 back, with the inner margins white; tail same color as the back, except the outer 

 margin of the exterior feather, and the inner webs of the others at the base, where 

 they are white; entire under plumage silvery-white; bill pale orange-yellow; iris 

 hazel; legs and feet light orange-red. 



Length, eight and three-quarters inches; wing, six and three-quarters; tail, three 

 and a half inches. 



Hal). — Texas to Labrador ; western rivers. 



This handsome little bird is of similar habits, and is 

 almost as abundant as tlie preceding. It breeds in the same 

 localities, and, like the others, nests on the beach or bare 

 rocks. The eggs are three in number. They are a rounded 

 ovoidal in form, and a grayish-cream tint in color : they are 

 marked with spots and confluent blotches of different shades 

 of brown and obscure-lilac, and vary in dimensions from 

 1.25 by .90 inch to 1.15 by .91 inch. A large number of 

 specimens from both the Southern and Northern States 

 exhibit no appreciable difference either in size or markings. 



HYDROCHELIDON, Boie. 



Hydrochelldon, BoiE, Isis (1822), 563. 



Bill rather short, strong, the upper mandible curving slightly to the tip; nostrils 

 basal, lateral, and longitudinal, the frontal feathers reaching nearly to the opening; 

 wings very long and pointed; tail moderate and emarginate; legs short; the ante- 

 rior toes slender, with the webs deeply indented; hind toe small; claws slender and 

 acute. 



HYDROCHELIDON PLUMBEA. — Wilson. 



The Short-tailed Tern. 



Sterna plumbea, "Wilson. Am. Orn., VII. (1813) 83. 



Sterna nifjra, Nuttall. Man., II. (1834) 282. Aud. Orn. Biog., III. (1835) 535; 

 V. (1839) 642. lb., Birds Am., VII. (1844) 116. 



Description. 



Adult. — Head, neck, breast, sides, and abdomen, black; lower tail coverts white; 

 under covering of wings ashy-gray; back and wings dark plumbeous-gray; the 



