PROTOZOA 95 



Fossil representatives of the order Dinoflagellata with a 

 cellulose skeleton are reported from the flint in the European 

 Cretaceous (Blitschli). 



CLASS C, SPOROZOA 



Parasitic Protozoa. There are no definite organs of locomo- 

 tion or of food-getting in the adult. Reproduction is typically 

 by the formation of seed-like bodies, — spores (whence the 

 name from Greek spora, seed, + zoon, animal). Each spore 

 contains one or more minute germs, — sporozoites. Unknown 

 in the fossil state. Gregarina and Plasmodium are two of the 

 common genera. Three different species of the latter may 

 cause human malaria. 



CLASS D, INFUSORIA 



Protozoa with a definite body outline. The organs of loco- 

 motion and food-capture during all or a part of their active 

 life are cilia, — small vibratile threads, smaller and more nu- 

 merous than flagella. There is a vegetative large macronucleus 

 and a smaller generative micronucleus. (The name was origi- 

 nally applied to all those minute plants and animals that make 

 their appearance in infusions of decaying organic substance, 

 but is now restricted to Protozoa as defined above.) Unknown 

 in the fossil state. Examples are Vorticella, Paramcecium and 

 Stentor. 



