150 ANSERES THALASSORNIS 



Genus XII. THALASSORNIS. 



Type. 



Thalassornis, Eyton, Mon. Anat. p. 70 (1838) T. leuconota. 



Bill short and stumpy, its depth at the base more than half its 

 length ; the sides about parallel ; culmen nearly straight ; nostrils 

 small and rounded ; nail very large, vertically down- turned and 

 pointed ; a nuchal crest ; wings short and rounded, the first three 

 primaries curiously attenuated for their distal third ; tail of 12 

 feathers, short, about a quarter the length of the wing but project- 

 ing well beyond the coverts ; the feathers narrow and stiff; tarsus 

 very short, about half the length of the middle toe ; hind toe with a 

 very broad lobe. 



Only the single species here described, confined to South and 

 East Africa, is referred to this genus. 



627. Thalassornis leuconota. White-backed Duck. 



Clangula leuconotus, S-niith, Cat. S. A. Mus. p. 37 (1837) ; id. Illnstr. 

 Zool. 8. Afr. Aves, pi. 107 (1846). 



Thalassornis leuconotus, Eyton. Monot/r. Anat. p. 168 (1838) ; Gurney, 

 Ibis, 1861, p. 134, 1862, p. 39 [Natal] ; PeUeln, Novara Beise, Vogel, 

 p. 139 (1865); Layard, B. S. Afr. p. 356 (1867); Gurney in 

 Andersson'a B. Damaral. p. 343 (1872) ; Ayres, Ibis, 1874, p. 105 ; 

 Butler, Feilden and Beid, Zool. 1882, p. 428; Sharped ed. Layard's 

 B. S. Afr. p. 761 (1884) ; Symonds, Ibis, 1887, p. 336 ; Nicolls and 

 Eglington, Sport *m. S. A. p.' 124, pi. xii, fig. 68 (1892) ; Bryden, Gun 

 and Camera, p. 407 (1893); -Fleck, Journ. Ornitli. 1894, p. 381; 

 Salvador^ Cat. B. M. xxvii, p. 436 (1895) ; Shelley, B. Afr. i, p. 173 

 (1896); Woodward Bros. Natal B. p. 212 (1899) ; Kciclienow, Voa. 

 Afr. i,p. 106 (1900) ; Hellmayr, Journ. OrnUli. 1902, p. 236 [Pienaars 

 River] ; Haaaner, Ibis, 1902, pp. 575, 08! ; Oates, Cat. B. l^'jys, ii, 

 p. 192 (1902). 



Description. Adult. Crown of the head, nape, sides of the face 

 and throat black, the black mingled with ochraceous yellow on the 

 sides of the face and neck ; a spot at the base of the upper mandible 

 and gape on either side whitish ; sides and front of the lower neck 

 rich fulvous yellow ; general colour above and below fulvous and 

 black, mottled and barred, palest in the middle of the breast where 

 the bars are almost absent ; centre of the back pure white, upper 

 tail- coverts black tipped with white ; tail-feathers stiff, narrow and 

 projecting, brown edged with fulvous; primaries plain dark brown, 

 no speculum. Iris dark brown ; bill blue and slate ; lower mandible 

 yellowish ; feet dark brown. 



