104 LAMELLIROSTRAL SWIMMERS — ANSERES. 



ated, consisting of eighteen very stiff, narrow feathers, with the shafts strong and rigid, and grooved 

 underneath, toward the base ; the tail-coverts extremely short, scarcely covering the base of the 

 tail ; wings very short, and very concave beneath, the primaries scarcely or not at all extending 

 beyond the tertials ; tarsus very short, much less than one half as long as the longest toe. 



In the characters defined above, all the known species which we have examined x agree strictly, 

 with the exception of Anas dominica, Linn., which has usually been referred to this genus, but which 

 differs radically in the character of the nail of the bill, this being broad and gradually curved, as 

 in other Ducks. This difference is so great that A. dominica should undoubtedly be separated 

 generically from the true Erismatura?,- among which the only important deviation in structure is 

 seen in E. leucocepliala, of Europe, which has the base of the maxilla much swollen both vertically 

 and laterally. 



The two American species of Erismatura may be distinguished as follows : — 



1. E. rubida. Bill, .90-.95 of an inch broad near the end. Adult male : Above, bright reddish 



ferruginous, including the whole neck, except upper part of the nape ; pileum and upper 

 part of the nape black ; entire side of head, below- the eyes, white ; lower parts whitish 

 (dark brownish gray beneath the surface, the breast tinged with buff). Adult female and 

 young male : Above, grayish brown, finely mottled, and sometimes indistinctly barred, with 

 grayish buff ; pileum darker brown, finely mottled with reddish ; rest of head grayish 

 white, crossed longitudinally by a stripe of mottled brownish, from the rictus back over 

 the auriculars, and parallel with the lower edge of the brown of the top of the head ; neck 

 pale brownish gray ; lower parts as in the adult male. Hub. North America, south to 

 Guatemala and West Indies. 



2. E. ferruginea. 3 Bill, .70-.85 of an inch broad near end. Adult male : Head and neck, 



except lower half of the latter in front, uniform black ; jugulum and upper parts deep 

 ferruginous, as in E. rubida; lower parts as in E. rubida. Adult female: Similar to E. 

 rubida but darker, and very distinctly barred on the sides and upper parts with fulvous- 

 buff. Hob. Southern South America. 



Erismatura rubida. 



THE RUDDY DUCK; SPINE-TAILED DUCK. 



Anas rubida, WlLS. Am. Orn. VIII. 1SI4, 12S, pi. 71, figs. 5, 6. 



Fuligula (Oymnura) rubida, Nutt. Man. II. 1834, 426. 



Fuligula rubida, Sw. k Rich. F. 15. A. II. 1S31, 455. — Aud. Orn. Biog. IV. 1838, 326, pi. 34:1 ; 



Synop. 1839, 2S8 ; B. Am. VI. 1843, 324, pi. 399. 

 Erismatura rubida, Bonap. Comp. List, 1838, 59. — Baird, B. N. Am. 1858, 811 ; Cat. N. Am. B. 



1859, no. 609. — Coues, Key, 1872, 295; Check List, 1S73, no. 519, 2d ed. 18S2, no. 741 ; 



Birds N. W. 1874, 583.— RlDGW. Norn. X. Am. B. 1881, no. C34. 

 Anas jamaiecnsis, Or.D, ed. Wils. VIII. 1825, 138. 



Hab. The whole of North America, breeding throughout its range, which extends south to 

 Guatemala and New Grenada ; Cuba. 



Sp. Char. Adult male, full plumage : Pileum and upper half of the nape uniform black ; entire 



1 E. rubida (Wils.), E. ferruginea (Eyton), of Chili, E. auslralis (Gould), of Australia, and E. 

 leucocepliala (Scop.), of Europe. There remains only E. moccoa, Smith, of South Africa. 



2 For " E." dominica we have already proposed the generic name Nomonyx (cf. Proc. U. S. Nat. Mas. 

 II. March 27, 1880, p. 15). 



3 Erismatura ferrugtkea. 



Erismatura ferruginea, Eyton, Monog. Anat. 1838, 170 (Chili). — Gray & Mitch. Gen. B. 1. 

 1844, pi. 169. —Cass. U. S. Astr. Exp. II. 1856, 204. — Scl. & Salv. P. Z. S. 1876, 404 

 (monographic) ; Nom. Neotr. 1873, 138. 

 Erismatura rittatu, Phil. & LANDB. Weigm. Archiv, 1860, 26 (Chili). 

 Tin 1 Australian E. uustralis closely resembles the South American species, but is rather larger and 

 deeper colored. 



