52 Zoologica: N. Y. Zoological Society. [I; 2 



The beak of the Hoatzin is peculiar in shape, and a better 

 idea can be obtained from the outline drawing, than from the 

 description alone. The mandibles are deep and wide, the aver- 

 age measurements of fifteen specimens being as follows : culmen 

 29mm., depth of mandibles at gape 22mm., width at gape 19mm. 

 The striking character of the mandible is the shortness of the 

 gonys — this being only about 9mm., or one-fifth of the total 

 length of the mandibles. The mandibles are slaty-olive, lighter 

 on the edges. The nostrils are round, and placed about midway 

 between the eye and the point of the beak. The sides of the 

 head are almost bare, being covered only with a very scanty 

 growth of black, bristle-like feathers on cheeks, ears and lores. 

 Two rows of these function as eye-lashes. The bare skin about 

 the eyes is nile blue in color, shading into cobalt on the other 

 unf eathered parts of the head. The irides are carmine. 



The bristles on the upper lores point upward, their tips in- 

 terlocking on the forehead. Just back of them begins the long 

 waving crest which is such a marked character of this species. 

 The crown feathers are reddish-buff; in those on the occiput the 

 buff darkens and becomes a shaft stripe, while the edges and 

 tips of the feathers are black. The longest measure about four 

 inches. The feathers of the upper parts as a whole are dark 

 brown, with a distinct olive-green iridescence. The feathers of 

 the nape and neck have pale, buffy shaft-stripes, this color 

 changing to white on the mantle. In some specimens the scapu- 

 lars are margined with white. The outer edges of the thumb 

 feathers are pale buff, corresponding in shade to the feathers of 

 the chin, throat and breast. Most of the wing coverts are tipped 

 more or less broadly with white, forming three distinct wing 

 bars. 



The under wing coverts and primaries are of a rich maroon 

 or chestnut, this hue being duplicated in the feathers of the 

 sides, belly, flanks, and most of the under tail-coverts. The tips 

 of the primaries are olive-green like the back, and the under and 

 upper tail-coverts are black. The tail consists of ten feathers 

 all of which are tipped with a broad band of buffy white. 



The Hoatzin harmonizes well with its environment, the dark 

 upper color and the splashes and streaks of white and buff 

 breaking up its body-form into sunlight and shadow. When 

 sitting quietly, either perching or on its nest, it is extremely dif- 

 ficult to detect, and its fear of hawks, shows that this conceal- 

 ment may perhaps serve a useful purpose. 



The most interesting thing about its coloration is the way 

 the colors of the under parts are carried out in the wings. The 



