INVERTEBRATE ZOOLOGY. 



PROTOZOA. 



Unicellular Animals. 



Class 1. Sarcodina. 



With changeable pseudopodia, during adult life. 

 Reproduction by simple division and by spore- 

 formation. 



Subclass 1. Rhizopoda. 



With lobose or reticulate pseudopodia. 

 Order 1. Amoebida. 



With lobose pseudopodia. (Amoeba, Arcella, 

 Difflugia.) 

 Order 2. Reticulariicla. 



With fine branching and anastomosing pseudopo- 

 dia. Shells, when present, usually calcareous. 

 (Alicrogromia, the Foraminifera.) 



Subclass 2. Heliozoa. 



Typically spherical in form. The pseudopodia, 

 which radiate from the entire surface of the body, 

 are ray-like, seldom changeable, and usuall}^ pos- 

 sess an axial filament. (Actinophrys, Actino- 

 sphserium, Clathrulina.) 



Subclass 3. Radiolaria. 



With ray-like pseudopodia, and with a chitinous 

 capsule inclosing the nuclei. The skeleton, when 

 present, is formed of silica or acanthin. All are 

 marine. (Thallassicolla.) 

 Class 2. Mastigophora. 



]\Iotile organs in the form of flagella. Repro- 

 duction by longitudinal division. Colony forma- 

 tion is frequent. 



Subclass 1. Flagellidia. 



With a definite anterior end on which there are 



