ECOLOGY OF THE HOATZIN BEEBE. 533 



The bare skin about the eyes is Nile blue in color, shading into cobalt 

 on the other unfeathered parts of the head. The irides are carmine. 



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

 ing 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 4 inches. The feathers of the upper 

 parts as a whole are dark brown, with a distinct olive-green irides- 

 cence. The feathers of the nape and neck have pale, buffy shaft 

 stripes, this color changing to white on the mantle. In some speci- 

 mens the scapulars pre 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 10 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 difficult to detect, and its fear 

 of hawks shows that this concealment 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 pale buffy 

 cream of the breast has spread, as it were, over the broad wrist edge 

 of the wing, and the rich chestnut of the belly has infiltrated through 

 the larger flight feathers. It is most difficult to account for this 

 correlation of limb and body patterns — a condition found in many 

 reptiles and insects — but it seems to emphasize the fact that some 

 important environmental factor or cause must be concerned with this 

 apparently directive evolution of just such colors being arranged in 

 just such patterns on totally different portions of the body. 



When the hoatzin is once alarmed, silhouetted against the sky, 

 with wings and tail spread, and crest waving, no more conspicuous 

 object can be imagined. 



The total length of the hoatzin is about 23 inches, the wing 12^, 

 the tail 12, tarsus 2, middle toe and claw 3. 



The single specimen already mentioned which I collected on the 

 Guarapiche differs from all the other hoatzins I have examined in 



