PREFACE. 



THE present work contains the substance of the six Lectures 

 on the Classification of Animals, which form the first part of 

 my "Lectures on the Elements of Comparative Anatomy," 

 published in 1864. 



That book has long been out of print, and I have not had 

 leisure to prepare a new edition of it; but I republish the 

 portion which relates to Classification, because I am told, on 

 good authority, that it is likely to be useful as a text book 

 to lecturers, and students attending lectures, on Comparative 

 Anatomy and Zoology. 



I have removed from the original text whatever discussions 

 seemed out of place in a text book, and I have added defini- 

 tions of all the most important orders of the Animal Kingdom. 



My best thanks are due to my friend Dr. PYE-SMITH for 

 the trouble which he has taken in seeing the work through 

 the press, and in preparing the Glossary. 



LONDON, MARCH, 1869. 



