520 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



Proc. Calif. Acad. Sci., 4th ser., ii, pt. 1, 1913, 19 (Grossman, Culpepper, and 



Wenman islands, Galapagos; habits; Clipperton Island and Oneal Rock, near 



Socorro Island). 

 S[terna]fuliginosa Rothschild and Hartekt, Novit. Zool., vi, 1899, 204 (Wenman 



and Culpepper islands). 

 Haliplana fuliginosa var. crissalis Lawrence, Proc. Best. Soc. N. H., xiv, 1871 



(pub. 1872), 285 (Socorro Island, Revillagigedo group, w. Mexico; coll. 



U. S. Nat. Mus.; ex Baird, manuscript); Mem. Bost. Soc. N. H., ii, 1874, 318 



(Socorro; Tres Marias). 

 Sterna fuliginosa crissalis Nelson, N. Am. Fauna, no. 14, 1899, 24 (Trea Marias 



Islands; Isabella Island; habits; crit.). — Bailey (H. H.), Auk, xxiii, 190G, 



378 (Isabella Island, w. Mexico, breeding). 

 Sterna fuscata crissalis American Ornithologists' Union Committee, Auk, xxv, 



July, 1908, 345. 

 [Sterna] crissalis Sharpe, Hand-list, i, 1899, 136. 



Genus STERNULA Boie. 



Sternula Boie, Isis, x, 1822, 563. (Type, by monotypy, Sterna minuta Lin- 

 naeu8=<S. albifrons Pallas.) 



Very small Sternidas (wing not more than 185 mm., usually con- 

 siderably less), with gonys much longer than mandibular rami; tail 

 only about half as long as wing, with lateral rectrices slender and 

 acuminate terminally, and tarsus not longer than middle toe with 

 claw. 



Bill about as long as head, rather slender, with gonys decidedly 

 longer than mandibular rami and with basal angle rather prominent; 

 latero-frontal antia nearer (in vertical line) to mental than to malar 

 antia. Wing long and pointed, the longest primary (outermost) 

 exceeding distal secondaries by more than twice the distance from 

 tips of the latter to bend of wing. Tail about half as long as wing, 

 forked for less than half its length, the lateral rectrices slender and 

 acuminate, or subacuminate, terminally. Tarsus slightly shorter 

 than middle toe with claw; webs with anterior margin slightly or 

 moderately incised. 



Plumage and coloration.— Occipitsd feathers normal (soft and 

 blended). Adults of most species with forehead and under parts 

 white (the latter sometimes gray), the rest of pileum (sometimes 

 whole pileum) and a loral streak black; back, wings, etc., pale gray. 

 Downy young buffy or bulfy-whitish above, sometimes nearly im- 

 maculate, but always ( ?) with more or less numerous irregular 

 markings of dusky. 



Range. — Nearly cosmopolitan. (About eight species, thi-ee of 

 them American.) 



key to the AMERICAN SPECIES AND SUBSPECIES OF STERNULA. 



a. Under parts white (or at most very faintly tinged with gray); tail pale gray. 



b. Smaller (wing less — usually much less — than 180 mm.); bill usually tipped 



•with blackish; black loral streak broader; color of back, etc., paler gray. 

 (Sternula antillarum.) 



