1909] Beebe: Ecology of the Hoatzin. 53 



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 pat- 

 terns, — 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 pat- 

 terns, 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 con- 

 spicuous 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 ex- 

 amined in having no buff on the crest, this color being replaced 

 by dark reddish chestnut ; the buffy cream of the breast is darker, 

 while the edges and shaft lines of the wing-coverts, mantle and 

 scapulars are buff instead of white, and the lower parts instead 

 of maroon are reddish buff. The bird is altogether unlike those 

 from other parts of South America. It is fully adult. 



Summing up the Hoatzin as a whole, we have a bird small 

 of body with small head, short, curved beak, long, waving crest, 

 and long, slender neck. The body plumage is loose and disinte- 

 grated, the wings and tail large in comparison with the body, 

 and of strong, well-knit feathers, — all the more remarkable when 

 we consider the weak flight, soon to be discussed. 



The shortness and stoutness of the beak may safely be cor- 

 related with the toughness of its vegetable food. Its short feet 

 rather belie their strength, as the bird seems to have little real 

 power in them, and is forever balancing itself with wings and 

 tail. 



Part VI — Parasites. 



The unpleasant odor which characterizes Hoatzins seems to 

 have no effect on their insect parasites, and the cheek bristles 

 are often encrusted with masses of the eggs of several large 

 species of Mallophaga. 



No thorough work has been done on the external parasites 

 of this bird, but I obtained three species of Mallophaga from the 

 Hoatzin shot on the Guarapiche River in north-eastern Vene- 

 zuela. Two of these insects are new species and I have pub- 

 lished their descriptions in Zoologica, Vol: 1, No, 4. I am in- 



