PREFACE. vii 



With very few exceptions, all the illustrations have been 

 drawn expressly for this work, with great care and fidelity, 

 by Mr. R. W. Sherwin, from specimens in the Museum of 

 the Royal College of Surgeons. 



September 2^1 ft, 1870. 



NOTE TO THE THIRD EDITION. 



This edition has been revised throughout. Several new 

 illustrations, a table shewing the number of the vertebra? 

 of a large number of species, and many references to the 

 more important recent memoirs on the subjects referred 

 to, have been introduced. 



Odobtr ist, 1885. 



