VI PEEFACE. 



can scarcely be undertaken by one possessing only 

 occasional opportunities for their study; but this 

 monograph it is hoped will help to show that a large 

 amount of inviting material lies ready to the hand 

 of the earnest student. 



The field is a wide one. Besides the structural 

 beauty of the Rhizopoda and the interesting phases 

 of their life-histories, the possibilities open to 

 anyone of discovering new and previously unsuspect- 

 ed forms in our ponds and marshes, are practically 

 unlimited. 



Whilst holding myself responsible for all micro- 

 scopic and descriptive Avork in the preparation of 

 this monograph, I desire to express my indebtedness 

 to Mr. John Hopkinson for the assistance which he 

 has rendered to me, particularly in working out the 

 synonymy of the genera and species described. This 

 has entailed upon him an expenditure of time and 

 labour which cannot be too generously acknowledged. 

 Mr. Hopkinson has in preparation a Bibliography of 

 the Freshwater Rhizopoda and Heliozoa which will 

 appear in a future volume of this work. 



To him I am also indebted for the suggestion of 

 the term Conchulina as applicable to the shelled 

 freshwater Rhizopoda. The discarded " Testacea " 

 a term pre-occupied in the Mollusca is unsuitable, 

 and its continued use is undesirable. Conchulina, 

 besides being strictly , accurate, is also especially 

 appropriate to these minute organisms. 



JAMES CASH. 



SALE, MANCHESTEB, 

 27th October, 1905. 



