EXTERNAL ANATOMY. APPENDAGES TO HEAD. 29 
particular purpose this latter structure is intended to 
answer^ it is impossible to form a correct idea. Were 
it confined to those groups which live upon putrid 
animal suhstanceSj like the vultures, where the naked- 
ness of the head is almost universal, it might be 
conjectured that, as the feathers of the head would be- 
come clotted with gore and putrid particles of the dis- 
gusting food of these birds, wliich were not within reach 
of the cleansing operation of the hill, this covering was 
desired : hut then w'e find that other birds, feeding only 
upon seeds and vegetables, like the turkey and the 
chatterers, have their heads also naked ; not to mention 
the jahiru, some of the cranes, and the great herons of 
India. These latter, however, and nearly all the bare- 
necked Gmlldtores, feed upon all sorts of things, living 
or dead, and may be almost considered as the vultures 
of their own order. 
(38.) 'I’he head is frequently ornamented with ap- 
pendages, either in the shape of horns, wattles, or crests : 
the first two are composed of fleshy or horny sub- 
stances ; but the latter, which are the most common, 
consist of lengthened feathers, which the bird can gene- 
rally erect or depress at pleasure. Although several 
birds have horn-like appendages, there is only one which 
has a real horn : this is the 
Palante/ka (Jiy. 10.), from 
the front of whose head 
issues a long spear-shaped 
horn, moveable, as we be- 
lieve, at its root, but per- 
fectly hard and compact in 
its substance, and which is 
used as a means of defence 
against its enemies. The Bmeridce, or hornbiUs, are 
remarkable for elevated processes, very much resembling 
horns, but which are no other than enlargements of 
the bill: tlie cassowary and the Guinea-fowl, however, 
Diay he said, perhaps, to have true horns, although 
uot of the shape usually understood by the term ; yet 
