512 THE DIVING BIRDS — PYGOPODES. 



which are a rictal plate and a broad, curved, posteriorly truncate shield covering the lateral base 

 of the mandible. Forehead ornamented by an upright recurved tuft of slender feathers, the tips of 



S. crisiaiellus. 



which overhang the bill ; head farther ornamented by a postocular series of slender white 

 filamentous feathers. Plumage plain — uniform dusky above, gray below. 

 A single species (S. cristafellus) Ijelongs to this genus, as here restricted. 



Simorhynchus cristatellus. 



THE CRESTED ATJK, 



Alca cristafdla, Pall. Spic. Zool. V. 1769, 20, pi. 3 and pi. 5, figs. 7, 8, 9. — Gmel. S. N. I. ii. 



1788, 552, no. 7. 

 Simorhynchus cristatellux, "M.Y.v.v.Y.'si" ViO^AV. Qom^i. Bend. XLII. 1856, 774. — Coues, Pr. Ac. 



Nat. Sci. Philad. 1868, 37 ; Key, 1872, 342 ; Check List, 1873, no. 622 ; ed. 2, 1882, no. 859 ; 



Elliott's Ala.ska, 1875, 206. — Riuaw. Nom. N. Am. B. 1881, no. 748. 

 Phnlcris cristatellus, Stepuexs, Gen. Zool. XIII, 1825, 47, pi. 5. — Cass, in Baird's B. N. Am. 



1858, 906. — Baird, Cat. N. Am. B. 1859, no. 719. 

 Phaleris superciliiitn, Aun. Orn. Biog. pi. 402 ; B. Am. VII. 1844, pi. 437 (not Mormon supcrciliosa, 



Light., = Alca pygmcca, Gm. ). 

 Uria dubia, Pall. Zoog. Rosso-As. II. 1826, 371, \i\. 87 (= young). 

 Simorhynchus duMus, CouEs, Pr. Ac. Nat. vSci. Philad. 1868, 40. 

 Alca tctracula, Pall. Spic. Zool. V. 1769, 23, pi. 4, and pi. 5, figs. 10, 11, 12. —Gmel. S. N.I. ii. 



1788, 552, no. 8. 

 Phaleris tetracrda, Cass. in Baird's B. N. Am. 1858, 907. — Baird, Cat. N. Am. B. 1859, no. 720. 

 Simorhynchus ictraculus, Coues, Pr. Ac. Nat. Sci. Philad. 1868, 43, fig. 9 ; Kej', 1872, 342. 



Hab. Coasts and islands of the North Pacific, from Kadiak and Unalashka through the 

 Aleutian chain to Kamtschatka and Northern Japan ; north to Prybilof Islands. 



Sp. Char. Adult, breeding-dres^s : Basal portion of the bill covered with complicated super- 

 numerary'- pieces, the most conspicuous of which is a detached semicircular concave plate situated 

 just above the rictus. Upper parts dusky blackish ; lower parts uniform smoky gray, shading 

 insensibly into the blackish of tlie upper parts. On the forehead a curled crest of narrow du.sky 

 brown feathers, curved forward in the greater part of a circle ; behind the eye, extending thence 

 back over the auriculars, a streak of narrow acicalar white feathers. Bill bright orange-red, the 

 end pale horn-color ; iris white ; legs and feet dusky in tlie dried skin. Adult, in winter (^ Alca 

 tctracula, Pallas) : Similar in plumage, even to the crest and white auricular fdaments ; but bill 

 very different, owing to the loss of tlie supernumerary basal pieces, being nuich smaller, smooth, 

 and destitute of the rictal shield, the broad expansion of the mandibular rami and nas;d shield ; 



