MR. R. OWEN ON THE ANATOMY OF THE CONCAVE HORNBILL, 121 
c@ca, appear to be adapted only for birds which, like the Hornbill and Toucan, live 
in the midst of plenty, and can select their food from both kingdoms of organized 
nature, so abundant and so prolific in a tropical clime. 
With respect to the differences observable between these remarkable genera, the 
principal instances are met with in the locomotive organs; and their affinities to 
other tribes, indicated by the obvious modifications of these parts, are confirmed by 
the differences observable in the internal organs. The Toucan resembles the Psit- 
tacide and other Scansores in the absence of a gall-bladder, while the Hornbill, in the 
capacity of that receptacle, manifests its affinity to the Corvide. I may also observe, 
that the same disposition of the intestinal canal in long and narrow loops, is met with 
in the Raven as in the Hornbill. It is well known that in treating of the modifications 
of the tongue in Birds, comparative anatomists derive their most remarkable examples 
from the Scansorial order: its superior organization for the sense of taste, from the 
Psittacide ; its remarkable structure as an organ of prehension, from the Picide ; and 
a third modification, equally curious, is presented by the Toucan, although the pur- 
poses for which this structure is adapted are less understood. The Hornbill, however, 
in the simplicity of this organ, resembles the carnivorous birds. 
The individual from which the preceding description was taken, was fed at the Gar- 
dens with small birds, mice, and pulpy fruits ; but it showed a decided preference for 
the animal diet, and would leave any kind of food if a dead mouse was thrown to it. 
This, after two or three squeezes with the beak, was gorged entire. It was never seen 
to regurgitate any castings; but I once observed it bring up repeatedly a portion of 
apple, which it endeavoured to crush with the points of the mandibles, and then again 
swallowed. Petiver gives direct testimony as to its regurgitating habits, for which, as . 
in the Toucan, the structure of the esophagus is well adapted. ‘‘ Calao vel Cagao In- 
dorum, Volucris & Montana est Avis, vivens fructibus Baliti s. fictis Ind. Sylv. Pilis, 
s. Amygdalo-Pistaceis, Volvuli Colyat, et aliis, quos integros ingurgitat ; confecto verd 
cortice carnoso, putamina ossea illzsis nucleis egerit.”! In sleeping, the bill is not dis- 
posed as ordinarily beneath the wing, but lies along the middle of the back with its 
point directed forwards, the cervical vertebre being acutely bent upon the dorsal: the 
Pelican disposes in a similar manner of its huge beak when asleep. The part of the 
wings corresponding ¢o the carpal joints overlap and defend the bill from cold. 
The Hornbill accommodates its habits and diet to the country in which it lives; 
being frugivorous in the Tropics, and feeding, like the Vultwres and Crows, on carrion in 
the desert plains of Abyssinia. We are told by MM. Quoy and Gaimard, that in the 
Papou Islands the Hornbill sits on the summit of the Nutmeg-tree, and with its 
large beak seizes the fruit, and swallows it entire. The length and wedge-like form 
of the mandibles are well adapted for pushing through thick and interwoven foliage 
without endangering the eyes and other soft parts about the head. I should consider 
1 Phil. Trans., vol. xxiii. p. 1394. 
