8o 



THE CLASSIFICATION OF PROTOZOA 



CLASS II.—RHIZOPODA 



Protozoa which have pseudopodia for most of their life histories, 

 and flagella, if at all, in young stages only. Besides forms like 



shell 



gas 

 vacuole 



nucleus 



ventral 

 opening 

 of shell 



B 



Fig. 47. — Testacea. 



A. Difflugia ; living individual, showing shell of sand grains and one pseudopodium ; B., Arcella; stained 

 individual with eight nuclei, dorsal view ; the opening of the shell is seen through the cytoplasm. 



Amceha (Order Amcebina) there are others with blunt pseudopodia 

 and shells (Testacea, Fig. 47), with shells and reticulate pseudo- 

 podia (Foraminifera), and with fine radial pseudopodia (Radio- 

 laria). The order Heliozoa has pseudopodia which have a stiff 

 supporting rod. Flagellate gametes are common throughout the 

 sub-class. 



CLASS IIL.—SPOROZOA 



This group is rather a waste-paper basket for parasites which 

 have no organs of locomotion except in young or distributive 

 stages, and includes forms of no particularly close relationship. 

 Many are intracellular in habitat at some stage in their life-history. 

 Examples are Monocystis and Plasmodium. The Cnidosporidia, 

 the only Protozoa with cells, are put here, though whether they 

 belong here is another matter. 



CLASS IV.—CILLOPHORA 



Protozoa with nuclei of two types, one concerned with somatic 

 matters and the other with syngamy, and cilia at some stage of 

 the life-history. There are two sub-classes — Suctoria, in which in 

 the adult the cilia are replaced by tentacle-hke structures (Fig. 

 48), and Ciliata, which bear cilia throughout life. The latter are 



