44 Mr. W. S. Macleay 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 caeca 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 

 PenduUnus has a muscular gizzard, although both these genera 



* " It is well known," says Paley in his Natural Theology, p. '271, " that there are 

 two 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 befuUof similar errors; which, 

 being in the hands of almost every one, are perpetuated by those who are ignorant of 

 Natural History. 



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