32 



BIOLOGY OF THE PROTOZOA 



rhizopods are relatively dense like that of the naked Amoeba verru- 

 cosa and are more or less globular or pyriform in shape. On such 

 a protoplasmic basis the shells of Dlfflugia species, Euglypha, Cyylw- 



: 



\ , 



Ik 



' 1 i 



•; n 







D 



Fig. 10. — Allogromia oviforme, foraminiferon with chitinous monothalamous shell 

 and reticulose pseudo podia. (£>) a recently captured diatom; OS) chitinous shell. 

 (From Calkins after M. Schultze.) 



deria, Centropyxis, Arcella, etc., are deposited and these, once 



formed, are never changed (Fig. 11). Only rarely are these shelled 



rhizopods flattened or discoid as in Hyalodiscus (see Chapter XII). 



The typical form in many shell-bearing or skeleton-forming rhizo- 



