VI PREFACE. 



the general nature and habits of a large number of animals, 

 and of the more important and striking of the phenomena of 

 animal life. To assist in giving the book utility in this 

 direction, I have endeavoured, in the index, to refer the 

 reader to the page on which technical terms are used for 

 the first time and explained. At one time I thought of 

 adding to each chapter a detailed account of some easily 

 accessible species belonging to^ the group with which it dealt, 

 but on reflection it appeared to me that such accounts were 

 not required; for we possess them in an excellent form in 

 many useful and well-known books, which are accessible to 

 everyone. Moreover, to have done so would have either 

 unduly increased the size of the book or rendered necessary 

 the omission of much interesting matter concerning the infinite 

 variation of animal structure and habits not found in works 

 easily accessible to students. 



Small print has been used for those parts of the work 

 which deal with disputed matters, or with subjects of a more 

 recondite character. It has also been employed for the 

 accounts of the families and genera which will be used 

 mainly for reference. By this means I have been able to 

 give far more information than would otherwise have been 

 possible. To further the same object I have used, in the 

 small print dealing with families and genera, not only 

 abbreviations, but also what has been called by a friendly 

 critic the style of the note-book. I very carefully considered 

 my critic's objection to this "note-book style," but I decided 

 that so long as I did not become unintelligible, the employ- 

 ment of it was justified by the object in view. Moreover, 

 I have been careful to limit its use to those parts of the 

 work which were apart from the main narrative, and would 

 be almost entirely used for purposes of reference. Most of the 

 abbreviations are explained in the index, and it is hoped that 

 no inconvenience will arise on account of their use. Authors' 

 names for genera are given throughout. It has been pointed 

 out to me, too late however for alteration, that the customary 

 abbreviations for those names are not always used, and that 

 my abbreviations have varied even on the same page. I am 



