PREFACE. 



THE design of this work is to furnish an epitome of the 

 leading principles of the science of Zoology, as deduced 

 from the present state of knowledge, so illustrated as 

 to be intelligible to the beginning student. No similar 

 treatise now exists in this country, and indeed some of 

 the topics have not been touched upon in the lan- 

 guage, unless in a strictly technical form, and in scat- 

 tered articles. On this account, some of the chapters, 

 like those on Embryology, and Metamorphosis, may 

 at first seem too abstruse for scholars in our common 

 schools. This may be the case, until teachers shall have 

 made themselves somewhat familiar with subjects com- 

 paratively new to them. But so essential have these 

 subjects now become to a correct interpretation of phi- 

 losophical zoology, that the study of them will hereafter 

 be indispensable. They furnish a key to many phe- 

 nomena which have been heretofore locked in mystery. 



Being designed for American students, the illustra- 

 tions have been drawn, as far as possible, from American 

 objects ; some of them are intended merely as ideal 

 outlines, which convey a more definite idea than if accu- 



