PREFACE. V 



between animals, and to appreciate the leading points upon 

 which classification is founded. 



Agassiz invariably placed before his students a single 

 specimen, or a box full of specimens, and told them to look 

 and see what they could find out. 



It has seemed, therefore, that the way to commence the 

 study of zoology is to follow the course one naturally pursues 

 when he is led to the study by predisposition. Nor is it es- 

 sential, at the outset, to present the entire range of the ani- 

 mal kingdom. Teach the characters of one or two great di- 

 visions first, and then the pupil is better prepared to gi-asp in 

 turn the other divisions. The persistent attempt, in all text- 

 books of this kind, to give some attention to every large 

 group in the animal kingdom, has often resulted in wearying 

 and confusing the minds of those who take up the study for 

 the first time. 



A very serious difiiculty is encountered in those books 

 which give a more or less complete view of systematic zo- 

 ology for beginners. In some, the authors commence with 

 the lowest forms, and end with the highest. In others, the 

 highest animals are dealt with first, and the lessons end with 

 the lowest. The first mistake made is the attempt to 

 teach systematic zoology, where the pupil is quite ignorant 

 of the material to be classified ; and proper familiarity 

 with the objects, the author contends, can only be acquired 



