9018 Birds. 
ventriculus succenturiatus. I say “representative of a gizzard,” 
because this organ is in every respect much feebler than a true 
gizzard in proportion to the size of the bird; indeed it appears to be 
rather an appendage to the ventriculus succenturiatus, in the form of 
a second stomach, than an independent organ. It is supplied with 
powerful muscles, which embrace the organ from certain fixed points, 
and which crush between them the contents of the organ. It is 
further supplied on its interior surfaces with a thickened and corru- 
gated membrane, and small stones are also found in its cavity, which 
had been swallowed by the bird to assist the organ in its grinding 
powers., The muscles are, however, mere representatives of those 
immensely developed muscles which render the ordinary true gizzard 
so irresistible in its grinding power. The thickened and corrugated 
lining membrane of the organ, too, is but a feeble type of those 
hardened fibrous plates which, in the true gizzard, forcibly rubbed 
together by vast muscular contraction, act as the mill-stones on the 
grain in an ordinary mill. The capacity also of the organ is com- 
paratively and relatively small, compared with the capacity of an 
ordinary true gizzard. 
This comparative inferiority in power and capacity is due, I con- 
ceive, to the fact that it has only a secondary part to play in the 
process of digestion, nor has it the food to retain for so long a period 
as an ordinary gizzard, whose office it is to keep up a sufficient 
supply of softened aliment for the nutrition of the bird, and that by 
its own unaided powers. It is a very interesting fact, however, and 
this wonderful arrangement of parts, so peculiarly fitted to the habits 
and requirements of those birds in which we find it, is worthy of 
note. 
In giving examples of birds occurring in each of the three classes 
I have spoken of, those named are selected, almost at random, from 
the unavoidably restricted list of birds whose stomachs I have actually 
examined, but which are nevertheless excellent illustrations of the 
peculiarities 1 have noted. 
The question then arises, why these various arrangements of 
stomach and varied powers of digestion in the great family of birds? 
May not the explanation be— 
1. That those birds in which a true stomach is found are birds 
feeding on animals, birds, fishes and insects, either sufficiently small 
to be digested in toto, bones and all, by the solvent powers of the 
organ, or birds which have the very peculiar power of rejecting the 
bones, hair, feathers, &c., in a mass subsequently to the removal of 
