PREFACE TO THE THIRD EDITION. 



Since the appearance of the former editions, the pubhcation of 

 the Junior Course of Practical Zoology by Dr. Hurst and 

 myself has completed, so far as Animal Morphology is concerned, 

 the Owens College Course of Elementary Biology. 



I have retained The Frog in its original form, as the mode of 

 treatment is more elementary, and in some ways different from 

 that of the larger book. The present edition has been carefully 

 revised, and an account of the development of the Frog has 

 been added. In preparing this account, I have had the 

 advantage of examining some excellent series of sections 

 mounted by my friends and former pupils, Mr. H. Sidebotham, 

 and Mr. A. E. Giles. 



Owens College, 



July, 1888. 



