Vlll PREFACE. 



Wasiliewski's Sporozoa, Pelseneer's Mollusca, and Benham's 

 Pulychaeta in the Cambridge Natural History. 



Of the illustrations about fifty are new, of the remainder 

 the majority are from Glaus' Leln^buch ; but some, which I 

 have been permitted to make use of by the courtesy of the 

 author and publishers, are from Bronn's Thierreich, Terrier's 

 Zoologie, Korschelt and Heider's Embryology, and Lang's Text- 

 book of Comparative Anatomy. 



In the classification the principal departures from precedent 

 concern the group of Ampkineura, which has been given up, 

 and the Gephyrea, which has been broken up into four inde- 

 pendent phyla. The reasons for these innovations are given 

 in the body of the work. 



The work will be issued in two volumes. The present 

 volume deals with the whole of the animal kingdom except 

 the Arthropoda, the Echinodermata, and the Chordata. The 

 treatment of these will be included in the second volume, in 

 the production of which I have been fortunate enough to 

 gain the co-operation of Mr. Lister. The second volume is 

 in preparation, and will, we hope, appear without any great 

 delay. It will, if possible, contain a part dealing generally 

 with the facts and principles of Zoology, but it may be 

 necessary, from considerations of size, to reserve this for a 

 third volume. 



