534 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1910. 



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 Amer- 

 ica, 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 disintegrated, 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 correlated 

 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. 



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 Mal- 

 lophaga. 



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 northeastern Venezuela, Two of 

 these insects are new species and I have published their descriptions 

 in Zoologica, vol. 1, No. 4. I am indebted for their descriptions, 

 and the following most interesting notes, to Dr. Vernon L. Kellogg, 

 of Stanford University. 



Concerning the Opisthocomus Mallophaga, Dr. Kellogg says: 



The three species are: 



(1) Ooniocotes ciirtus Nitzsch. — Heretofore taken from Opisthocomus aud no 

 other host. 



(2) Lipeurus, sp. nov. — lu the group clypcata siitura distincta, which group 

 has been found heretofore only on maritime birds. 



(3) Colpoccphalum sp. nov. — ^An extraordinarily spiny beast, not much like 

 anything else in the genus. 



I am disappointed in finding these two new species. I hoped to find known 

 parasites that might, by their relationship with other parasites, characteristic 

 of the pheasants or the rails or some other group of birds, be a clue to the 

 indication of your curious bird's phyletic affinities. 



The one known species of parasite, the Ooniocotes, belongs to a group of 

 Mallophaga best represented, and most characteristically, on the pheasants. 

 But the Lipeurus, although a new species, belongs just as unmistakably with a 

 group of Mallophaga chai-acteristic of such birds as boobies, albatrosses, cor- 

 morants, frigate birds, pelicans, and such strictly maritime forms. 



