THE HOATZINS. 259 
Sexes similar in plumage. 
An elongate crest of rather stiff-shafted feathers sides of 
the head mostly naked. 
Tail composed of zem feathers, elongate and rounded; the 
middle pair considerably longer than the outer pair. 
First primary flight-feather much shorter than the second, 
which is shorter than the tenth; sixth to eighth longest. 
Fifth secondary quill present. 
Tarsus with reticulated scales, shorter than the middle toe 
and claw. 
I. THE HOATZIN. OPISTHOCOMUS HOAZIN. 
Phastanus hoazin, Mill. S. N. Suppl. p. 125 (1776). 
Crested Pheasant, Latham, Gen. Syn. ii. pt. ii. p. 720, pl. Ixiv. 
(1783). 
_Phasianus cristatus, Gmel. 8. N. 1. pt. ii. p. 741 (1788). 
Opisthocomus hoatzin, Steph. in Shaw’s Gen. Zool. xi. p. 193 
(1819). 
Opisthocomus cristaius, L)Herminier, C. R. v. p. 433 (1837); 
G. R. Gray, Gen. B. ii. p. 396, pl. xcvii. (1845); Huxley, 
P. Z.S. 1867, pp. 435, 460, 1868, p. 304 [skeleton], fig. 4, 
pl. xeviil. (1845) ; Cabanis, J. f.O. 1870, p. 318, pl. i. fig. 3 
[egg]; Perrin, Trans. Z. S. ix. p. 353, pls. 63-66 (1875) ; 
Garrod, P. Z. S. 1879, p. 109 [anatomy] ; Quelch, Ibis. 
1890, p. 327 [habits]; Parker, Trans. Zool. Soc. xiii. pp. 
43-86, pls. vii.—x. (1891); Gadow, P. R. Irish. Ac. (3) ii. 
p- 147, pls. vil. viii. (1892). 
Opisthocomus hoazin, Ogilvie-Grant, Cat. B. Brit. Mus. xxii. 
Pp. 524 (1893). . 
(Plate XL.) 
Adult Male and Female—General colour above dark brown 
glossed with olive ; fore part of the head reddish-brown ; long 
crest-feathers mostly dark brown; feathers on the back of the 
neck and mantle similar, but the former with buff and the latter 
with white shaft-stripes ; the shoulder-feathers and wing-coverts 
either margined or tipped with white; quills chestnut-brown ; 
Ss 2 
