PREP ACE. 



and I can only hope that I may in some measure 

 have repaid him for it by turning to account the 

 material which he has so hberally suppUed, in the 

 interests of our favourite science. 



My old friend and ally Mr. Peach has kindly 

 helped me, both with his rich collections and his 

 large experience as a practical naturalist. 



To Dr. M'Intosh I am indebted for interesting 

 specimens, and, still more, for very valuable suggestions 

 and for the communication of his views on some of 

 the difficult problems with which I have had to deal. 

 Professor Ray Lankester has most obhgingly fur- 

 nished me with information which I needed respect- 

 ing those branches of my subject on which he is so 

 high an authority. 



Mr. Leipner has freely supplied me with his beau- 

 tiful mountings of the Polyzoa, in which they may 

 be studied almost as when livnig — and has thus 

 given me most important assistance, especially in 

 the investigation of the Ctenostomatous forms. 



To Mr. Alfred Bell I owe an extensive list of 

 Polyzoa from the Upper and Post-Tertiary deposits, 

 accompanied by valuable notes on the character and 

 arrangement of the beds. 



I have to thank Principal Dawson, of M'Gill Uni- 

 versity, Montreal, for a very interesting series of 

 species from the St. Lawrence and from the Cana- 

 dian Post-Pliocene deposits, which he has so ably 

 investigated. 



To' Dr. J. Barrois, of Lille, I am under peculiar 

 obligations for his courtesy in permitting me to re- 



