PREFACE 



This book is a revised edition of the author's "Course in In- 

 vertebrate Zoology," to which have been added the two dis- 

 sections, abbreviated and simpUfied, of the perch and the frog 

 from his ''Course in Vertebrate Zoology." The main purpose of 

 this combination is to enable classes using the book to study rep- 

 resentatives of vertebrates together with invertebrates, and thus 

 to become acquainted with the structure of all the phyla of the 

 animal kingdom. 



In making this revision the author has not changed the char- 

 acter of the work or the order of the dissections ; all those ap- 

 pearing in the ''Invertebrate Zoology" are also given here. The 

 plan of the course is to study each of the larger groups of the 

 animal kingdom as a whole as far as possible, instead of detached 

 types of the different groups taken more or less at random. The 

 attention is directed constantly to the main structural features 

 which characterize the entire group under consideration, and the 

 study is thus made comparative. 



In order that the systematic position of the animals examined 

 and their larger affinities may be easily kept in mind, the names 

 of the most important systematic groups to which the animal 

 being studied belongs are placed at the head of each dissection, 

 and a synopsis of the whole animal kingdom has been added in 

 an appendix. 



The course begins with arthropods, because the natural suc- 

 cession of forms in the animal kingdom, from the lowest to the 

 highest, is more apparent in them than in any other group, except 

 possibly in vertebrates, and it is easy for a beginner, by studying 

 them, to learn the real significance of the blood relationship of 

 animals. Whether, however, the student begins the course with 

 insects or with crustaceans, and whether the first insect taken 

 up is the wasp or the grasshopper, will be matters for the deci- 



