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 extri'nioly generalized character, but as the Ansercs jirol>- 

 ablv have developed out of an ancestor in wliicii the j)luinage was ecpially uninter- 

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

 liarity of the screamers is the extreme ])neuniacity, not only of the bones, nearly every 

 one of which is j)ernieated 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 univereally emphysematous to the depth of 

 nearly a quarter of an inch. On ])ressing with the finger, the characteristic crackling 

 of a tissue tilled 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 dee]> layer another, with the air-cells 

 intervening lietween them, and the feather-quills traversing them. In ( 'hauna, however, 

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

 if a non-cm])hysen)atous skin had been forcibly blown n]>, so as to cause its surface to 

 be irregular and Inibbled, more like an artiticially distended mammalian lung tlian any- 

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

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

 aj>i)earance of the legs is also caused by the ])resence of air beneatli the tessellated 

 skin, which extends almost to the ungual ]>lialanges of the toes." 



In the bill the Axiiimid.e differ considerably from the ducks and flamingos. 

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

 neither lamclloso-deiitatc nor covered with a soft skin. Other external characters of 

 importance are the long and dispro))ortionately thick legs, the long toes, the low hind 

 toe, and the long and straight claws. 



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

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

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

 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 s])ecies of the genus Vhaiam, 

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

 armed with two strong s])incs, 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 su<ldcn hoot, very 

 different from the scream of the ehahas. 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 

 ap])earanee ; and when such is the case with one individual, the impression j)roduced 

 by seeing a hundreil 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 Ajn-es], on 

 which, at certain seasons of the year, I have fre(iuently seen that number, not collected 

 into a flock, but in ]iairs. The swainps and ijrackish lagoons constitute its haunts and 

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

 water and swim with only a very small portion of its body immei-sed ; but it ])refers to 

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



I 



