520 



THE DIVING BIRDS — PYGOPODES. 



compressed vertical process of the nasal shield, characteristic of the Vn-eeding-season. When the 

 latter is cast, the iipi)er outline of the cere is nearly straight, and depressed decidedly below the 

 level of the base of the culnien. Head ornamented by fonr (two on each side) longitudinal series 

 of filamentous white feathers. Plumage dull-grayish dusky above, whitish below, the under side 

 of the head and neck brownish gray. 



C. iTwnocerata, summer adult. 



C. monoccrata, ivmter adult. 



Of this remarkalde genus but one species is known ; this having given ornithologists nuich 

 trouble before the deciduous character of the nasal horn and mandibular process was fully under- 

 stood ; the same species in winter plumage, with these appendages absent, being referred to a 

 different genus Q^ Sagmatorhina"). 



Cerorhyncha monocerata. 



THE HORN-BILLED AUK. 



Jlca monocerata, Pall. Zoog. Eosso-As. II. 1826, 362, no. 414. 



Ccrorhhia monocerata, Cass, in Baird's B. N. Am. 1858, 905. — BAinn, Cat. N. Am. B. 18.^9, no. 717. 



Ccratorhyncha monoccrata, CouES, Pr. Ac. Nat. Sci. Philad. 1868, 28, figs. 1, 2. 



Ceratorhina monocerata, Coues, Key, 1872, 341 ; Check List, 1873, no. 620 ; cd. 2, 1SS2, no. 8r>7. — 



PiDGW. Norn. N. Am. B. 1881, no. 620. 

 Phalcris ccrorJu/nca, Boxap. Zool. Jouvn. 1827, 53. 

 Ccrorhinca occidcntalis, Bonap. Ann. Lye. N. Y. (Synop. N. Am. B. ) IV. 1828, 428. — Nutt. Man. 



n. 1834, 538. 

 Ceratorhina occidcntalis, Aui). Orn. Biog. V. 1839, 104, pi. 402, fig. 5. 

 Uria occidcntalis, AuD. B. Am. VII. 1844, 364, pi. 471. 



Cerorhina orientalis, Brandt, Bull. Ac. St. Petersb. II. 1837, 348 {lapsus calami for occidcntalis').). 

 Chimerina cornuta, Eschscholtz, Zool. Atl. III. 1829, 2, pi. 12. 

 Cerorhina Sucklcyi, Cass, in Baird's B. N. Am. 1858, 906 (adult without knob on bill). — BAUxn, 



Cat. N. Am. B. 1859, no. 718. 

 Sagmatorhina Sucklcyi, CouEs, Pr. Ac. Nat. Sci. Philad. 1868, 32, figs. 4, 5 (bill). 

 The Horn-billed Guillemot, Cass. & Baiiid, 11. c. 



Hab. Coasts and islands of the North Pacific, breeding as far south as California (Farallon 

 Islands) and Northern Japan ; in winter, as far as Lower California. 



Sp. Char. Adult, hreedimj flumaye : Entire upper parts dull brownish black, the feathers some- 

 times with paler or grayish brown tips ; lateral and under parts of liead and neck, jugulum, and 



