v1 PREFACE. 
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 imicro- 
scopic and descriptive work 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, MANCHESTER, 
27th October, 1905. 
