44 Mr. W.S. Macueay on the Comparative Anatomy 
presents something better than the disjointed ruins of a once 
beautiful fabric. 
Confining myself now to the class of Birds, and deeming the 
structure of their beak, wings and feet, to be points of external 
anatomy, I conceive that part of their internal structure, which 
is next in importance to the naturalist after the vertebral axis, to 
be the digestive apparatus; since on this depends the nature of the 
food, and consequently the mode of living of the individual. 
Hence the variation of structure in the crop, glandular crop, 
gizzard, intestines, and ceca of Birds, ought particularly to 
be studied; and, in fact, has always excited a considerable 
portion of ornithological attention. Yet unfortunately, from 
that natural tendency which we all more or less possess to 
generalize carelessly, there has been made a grand division 
of Birds into Carnivorous and Herbivorous, where the former 
was characterized by a membranaceous stomach, and the lat- 
ter by a strong muscular gizzard*. Now this is all erroneous; 
the fact being that although the length of the intestine may have 
some relation to the animal or vegetable nature of the food, the 
muscular structure of the gizzard depends only on its degree of 
hardness. ‘Thus Birds destined by nature to feed on soft vege- 
table matter, have a membranaceous stomach; and those in- 
tended to prey on hard animal matter, such as Coleopterous or 
Hymenopterous insects, have a muscular gizzard for trituration. 
The Humming Bird has a membranaceous stomach ; while the 
Pendulinus has a muscular gizzard, although both these genera 
* <« Tt is well known,” says Paley in his Natural Theology, p. 271, “ that there are 
iwo intestinal systems found in birds :—one with a membranous stomach and a gastric 
juice capable of dissolving animal substances alone; and the other with a crop and 
gizzard calculated for the moistening, bruising, and afterwards digesting of vegetable 
aliment.” It is much to be regretted that this work should be full of similar errors; which, 
being in the hands of almost every one, are perpetuated by those who are ignorant of 
Natural History. 
suck 
