774 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



Genus JETHIA Merrem. 



Aethia « Merrem, Verz. Grundr. AUg. Gesch. u. Nat. Eintheil. d. Yog., i, Tenta- 

 men Nat. Syst. Av., i, 1788, pp. 7, 13, 20. (Type, by monotypy, Alca 

 cristatella Pallas. See Uartert, No\'it. Zool., xxiii, 1916, 340.) 



Simorhynchus Merrem, in Ersch u. Gruber'a Encycl., 1 sec. ii, 1819, 405. (Type, 

 by original designation and monotypy, Alca cristatella Pallas.) 



Tyloramphus Brandt, Bull. Acad. St. Petersb., ii, 1837, 348. (Type, Alca crista- 

 tella Pallas.) 



Medium-sized Phalerinas (wing 125-143 mm.) with exposed culmen 

 less than half as long as commissure and not longer than gonys; 

 adults with a slender recurved frontal crest and line of postocular 

 acicular plumes, and in breeding season a conspicuous concave supra- 

 rictal horny plate and conspicious enlargement of the mandibular 

 rami. 



Bill short and stout, its depth from base of exposed cuhnen to 

 gonydeal angle much greater than its width at same point and at 

 least equal to length of exposed cuhnen, the latter strongly curved; 

 gonys as long as or longer than exposed cuhnen, faintly convex, 

 ascending terminally, its basal angle more or less prominent; maxil- 

 lary tomium strongly convex basally, distinctly incised terminally, 

 the tip of maxilla distinctly uncinate; mandibular tomium nearly 

 straight in middle portion, recurved terminally, recurved and arched 

 basally, the tip of mandible recurved, with tip obliquely truncate; 

 mandibular rami mostly unfeathered (wholly so in breeding season), 

 equal to or longer than gonys; nostril longitudinal, narrowly ovate 

 (its anterior end acute), overhung in breedmg season by the lower 

 edge of a prominent supra-nasal saddle or cuhass; anterior line of 

 frontal feathering extendmg almost straight across base of culmen, 

 nearly on line (vertically) with middle of nostrils, the mental antia 

 slightly posterior to it. Wing moderate, the longest primary (outer- 

 most) exceeding distal secondaries by slighty less than half the 

 length of wing. Tail about tliree-sevenths as long as wing, slightly 

 rounded; rec trices 14. Tarsus decidedly shorter than middle toe 

 without claw, the acrotarsium reticulate; outer toe (without claw) 

 as long as middle toe (without claw), the inner toe as long as first two 

 phalanges of middle toe; claws rather small, only moderately curved 

 and acute. 



Nuptial ornaments. — A conspicuous supra-rictal horny plate, with 

 concave surface; mandibular rami conspicuously enlarged, and 

 supra-nasal saddle or cuirass prominent and corneous. 



Plumage and coloration. — xVdults with a conspicuous frontal 

 strongly recurved crest of slender, elongated feathers (much as in 

 Alcella) and with a narrow Ime of slender acicular white feathers 



« AWvLa, a sea-bird of some kind. (Richmond.) 



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