BIRDS OF NORTH AND MIDDLE AMERICA. 461 



toe,, the gonys more than half as long as mandibular rami; nostril 

 considerably anterior to latcro-frontal antia, narrowly elliptical, 

 longitudinal; latero-frontal antia nearer to vertical line from mental 

 antia than to that from jnalar antia. Wing long and pointed, the 

 longest primary (outermost) exceeding distal secondaries by nearly 

 twice the distance from tips of the latter to bend of wing. Tail a 

 httle more than one-third as long as wing, forked for between one- 

 fourth and one-third its length, or even less, the rectrices (except 

 middle pair) contracted terminally, especially the outermost pair, but 

 not acuminate. Tarsus longer than middle toe with claw, nearly 

 half as long as bill from rictus; anterior toes fully webbed. 



Pluma;/e and coloration. — Occipital feathers distinctly but not con- 

 spicuously elongated, soft and blended. Adults pale gray above 

 with black pileum, under parts immaculate wliitc; inner webs of 

 primaries unicolored, or at least not distinctly bicolored; bill red; 

 downy young unspotted. 



Range. — Nearly cosmopolitan, but wanting in Central and Sou 

 America, West Indies, and Pacific islands. (Monotypic.) 



HYDROPROGNE CASPIA (Fallas). 



CASPIAN TERN. 



Adults in breeding plumage (sexes alike). — Enti '>\ pileum, including 

 upper half of lores and auricular region and part, of suborbital region, 

 uniform deep black, the lower eyelid with a crescentic streak of white; 

 rest of upper parts pallid neutral gray, fadinjj into white on upper 

 tail-coverts, the tail grayish white; inner webs of primaries uniform 

 dark hoary gray or slate color; rest of plumage immaculate pure 

 white; bill deep coral red, duUer subterminally, the tip orange or 

 yellowish; iris dark brown; legs and feet black. 



Adults in post-nuptial plumage. — Similar to the breeding plumage 

 but black on pileum more or less intermixed with white. 



Adults in winter. — Similar to the post-nuptial plumage but with 

 pileum, etc., streaked with white; bill more orange-red. 



Young. — Upper parts pale grayish with a few roundish or more or 

 less hastate spots of dusky, largest on tertials; pileum grayish white, 

 the crown flecked with black, this increasing in extent posteriorly 

 until nearly uniform dull black on occiput and nape; rectrices with 

 a sub terminal spot of dusky; under parts white; bill dull orange- 

 reddish, more dusky terminally or subterminally. 



Doiony young. — Upper parts grayish white, the down of pileum 

 dusky gray beneath surface; back and rump linely and indistinctly 

 mottled with grayish; throat and foreneck uniform pale grayish, the 

 remaining under parts white. 



