358 PROTOZOOLOGY 



and Oxncrella (Fig. 55), tho central granule behaves somewhat 

 like the centriole in a metazoan mitosis. Budding has been 

 known in numerous species. In Acanthocystis the nucleus under- 

 goes amitosis several times, thus forming several nuclei, one of 

 which remains in place while the other migrates toward the body 

 surface. Each peripheral nucleus becomes surrounded by a pro- 

 truding cytoplasmic body which becomes covered by spicules 

 and which is set free in the water as a bud. These small individuals 

 are supposed to grow into larger forms, the central granules being 

 produced from the nucleus during the growth. Formation of 

 swarmers is known in a few genera and sexual reproduction occurs 

 in some forms. The Heliozoa live chiefly in fresh water, although 

 some inhabit the sea. 



Without gelatinous envelope 

 Without flagella 



Ps'eudopodia arise from thick basal parts, branching 



Family 1 Actinocomidae 



Pseudopodia not branching; cytoplasm highly vacuolated 



Family 2 Actinophryidae 



With 1-2 flagella Family 3 Ciliophryidae (p. 359) 



With gelatinous envelope; with or without skeleton 

 Without flagella 



Without chitinous capsule 



Without definite skeleton .... Family 4 Lithocollidae (p. 360) 

 With chitinous or siliceous spicules or scales 



With chitinous spicules. . .Family 5 Heterophryidae (p. 362) 

 With siliceous skeleton 



Cup-like plates over body; 2-3 pseudopodia often grouped 



Family 6 Clathrellidae (p. 362) 



Scales flattened, not cup-like 



Family 7 Acanthocystidae (p. 362) 



With chitinous retiform capsule. Family 8 Clathulinidae (p. 364) 



With numerous flagella, among axopodia; siliceous scales 



Family 9 Myriophryidae (p. 366) 



Family 1 Actinocomidae Poche 



Genus Actinocoma Penard. Body spherical; one or more con- 

 tractile vacuoles; nucleus with a thick membrane, central; filo- 

 podia, not axopodia, simple or in brush-hke groups; fresh water. 



A. ramosa P. (Fig. 163, a). Average diameter 14-26^1. 



Family 2 Actinophyridae Glaus 

 Genus Actinophrys Ehrenberg. Spheroidal; cytoplasm highly 

 vacuolated, especially ectoplasm; with often symbiotic zoochlorel- 



