ALCIDA — PHALERIDINA: AUKS. 805 
pieces; the change in upper mandible is decided, as in F. arctica, but the difference in the 
lower mandible is comparatively slight. In birds of the first spring the terminal portion of the 
bill may be smooth, like the under mandible, and the bill and feet rather orange-red than ver- 
milion ; at this time the face whitens and the crests sprout. Young: No crests, and no white 
about the face 
The bill like that 
of the adults in 
winter after the 
moult, saddled 
with soft dark-col- 
ored skin at base, 
but every way 
smaller, weaker, 
and quite smooth 
( ‘* Sagmatorhina 
lathami,” fig. 535,) 
and, like the feet, 
rather yellow or 
orange than red; the plumage entirely blackish above, sooty- brown below, the feathers of the 
belly and flanks whitish at the base; iris brown. Coasts and Islands of the N. Pacific, S. in 
winter on the American side to California; of casual occurrence on the Atlantic Coast to New 
England. General habits and economy of the common puffin; nesting similar. Egg single, 
rough, dead-white, but showing, besides frequent discolorations, obsolete shell-markings of 
pale purplish-gray ; size from 2.65 to 2.85, by 1.92 to 2.00; broader and more eapacious than 
that of F’. corniculata, though no longer. 
CERATORHI'NA. (Gr. xépas, xépatos, keras, keratos, a horn; pis, pivds, hris, hrinos, the 
nose.) Ruryoceros AuxKs. Related to Lunda and Fratercula ; no peculiarity of eyelids or 
inner claw; bill smooth; 
base of upper mandible 
with a large upright 
horn, and under mandi- 
ble with an accessory 
horny piece lying be- 
tween its rami; this 
piece and the horn decid- 
uous, when base of up- 
per mandible covered 
with a soft cere. Bill 
shorter than head, stout, Fic. 538. — Horn-billed Auk, young, nat. size. (From Elliot.) 
deep at base, much compressed and rapidly tapering to acute decurved tip, sides erect, smooth, 
culmen very convex, gape gently curved, gonys nearly straight, with angle at symphysis. 
Nostrils short, linear, subbasal, marginal, impervious, at base of the horn or cere. Two 
series, postocular and maxillary, of lengthened, straight, stiffish lance-acute white feathers on 
each side of head. General form of Fratercula. Size large. One species. 
C. monocera/ta. (Gr. povos, monos, only, single; xépas, keras, horn. Figs. 536, 537, 538.) 
Unicorn AuK. Horn-pini Aux. Adults in summer: Bill orange-yellow. Culmen and 
base of upper mandible dusky ; feet some yellow color, the tarsi behind and the soles blackish ; 
claws black. The sharp feathers of the head white, about an inch long. Entire upper parts 
glossy blue-black; a line of white along edge of forearm. Sides of head and neck, of body 
along under the wings, with chin, throat, and fore-breast, clear grayish-ash, or pale bluish- 
Fie. 537. — Horn-billed Auk, adult in winter, nat. size. (From Elliott.) 
