vi INTRODUCTION TO ZOOLOGY 



student's mind, but fall into place as representatives of the 

 varied branches of the animal kingdom. It is, however, 

 strongly recommended that the practical study should always 

 precede the reading of the chapter dealing with the type under 

 investigation. 



It is hoped that this book may be of use to pupils in the 

 top classes of secondary schools ; to the students of " Nature 

 Study " in Training Colleges ; perhaps also to those entering 

 upon a systematic course of Zoology such as that in prepara- 

 tion for University examinations, who may feel the need of 

 some first-hand knowledge of the living creatures which, in 

 their academic course, they usually meet only as dead labora- 

 tory specimens ; and finally to those students, working alone, 

 who may desire some guide as to what path to follow in the 

 wide field of Natural History, and for whose sake numerous 

 references are given to books where fuller information may 

 be obtained. 



The book deals almost entirely with the habits and external 

 structure of common British Invertebrate animals ; occasion- 

 ally a few points of internal structure have been touched 

 upon, either because a knowledge of them was necessary 

 for the explanation of the external phenomena, or because 

 they must be known before the relationships of the various 

 types of animals described could be appreciated. Microscopic 

 structure is only given in a few of the first types, where it 

 seemed to be desirable in order to illustrate some of the 

 stages in the evolution of a more complex form of body 

 from the simple unicellular form. 



The types described in this book include those Inverte- 

 brates which occur in the syllabuses for the National Froebel 

 Union, the Cambridge (junior and senior) Local examinations, 

 and also, with one or two exceptions, those of the Board of 

 Education (South Kensington) (Stages 1, 2, and 3) and of the 

 Central Welsh Board. 



The statement given above explains to some extent why 

 this book has been published : why it has been written is 



