134 NATURAL HISTORY OF BIRDS. 



feathers and downs are evenly dispersed over the body, with only an apterium in each 

 axillary cavity. This is an extremely generalized character, but as the Anseres prob- 

 ably have developed out of an ancestor in which the plumage was equally uninter- 

 rupted, it bears only little upon the relationships of the group in question. A pecu- 

 liarity of the screamers is the extreme pneumacity, not only of the bones, nearly every 

 one of which is permeated by air, but also of the cutaneous system. As this feature 

 merits attention, we quote Garrod's description nearly in full : " The most striking 

 point observed in the plucked bird is the extreme whiteness of the surface, which de- 

 pends on the fact that the skin is almost universally emphysematous to the depth of 

 nearly a quarter of an inch. On pressing with the finger, the characteristic crackling 

 of a tissue filled with air is most marked. ... In the gannet and the pelican the skin 

 is likewise emphysematous, but not exactly in the same way. In them the superficial 

 surface of the cutis forms a plane surface, and the deep layer another, with the air-cells 

 intervening between them, and the feather-quills traversing them. In Chauna, however, 

 these two cutaneous layers are not definable, the whole presenting the appearance as 

 if a non-emphysematous skin had been forcibly blown up, so as to cause its surface to 

 be irregular and bubbled, more like an artificially distended mammalian lung than any- 

 thing else. The feathers and the semi-plumes do not perforate the air-cells, but cause 

 the skin to be indented where they are situated. The disproportionately massive 

 appearance of the legs is also caused by the presence of air beneath the tessellated 

 skin, which extends almost to the ungual phalanges of the toes." 



In the bill the ANHIMID^E differ considerably from the ducks and flamingos. 

 It is short vaulted, and, on the whole, somewhat Gallinaceous in its form, being 

 neither lamelloso-dentate nor covered with a soft skin. Other external characters of 

 importance are the long and disproportionately thick legs, the long toes, the low hind 

 toe, and the long and straight claws. 



The habitat of these birds is tropical and temperate South America. The family 

 is a very small one, consisting of only three species belonging to two genera. Anhima 

 cornuta (or Palamedea cornuta), the species figured, is a most curious and unique 

 looking bird, being a true avian ' unicorn.' From the forehead rises a thin, forward- 

 curved horn, five to six inches long, and, as in the species of the genus Chauna, 

 which have no horns, but naked lores and a long, occipital feather-crest, each wing is 

 armed with two strong spines, the larger one at the bend, the other further down on 

 the hand. The horned-screamer does not seem to deserve its name as much as the other 

 two species, for the sound emitted by it is said to be a loud and sudden hoot, very 

 different from the scream of the chahas. They are all said to be tamed and employed 

 by the natives as herders and protectors to the poultry which they defend against birds 

 of prey and other enemies. Mr. E. Gibson has recently given the following account of 

 the habits of the crested-screamer : 



" C. chavaria is, as may well be imagined, a most striking bird, both in size and 

 appearance; and when such is the case with one individual, the impression produced 

 by seeing a hundred pairs together is not likely to be less. There is a large island 

 among a network of swamps a mile from here [Cape San Antonio, Buenos Ayres], on 

 which, at certain seasons of the year, I have frequently seen that number, not collected 

 into a flock, but in pairs. The swamps and brackish lagoons constitute its haunts and 

 feeding-grounds. On one or two occasions I have seen a bird alight in the deeper 

 water and swim with only a very small portion of its body immersed ; but it prefers to 

 wade where the marsh is shallower. But what most excited my astonishment was 



