6 RHIZOPODA. 



Order 6. Heliozoa. Globular Rhizopods, with fine stiff radiating 

 pseudopodia. Protoplasm containing one or more nuclei and contractile 

 vacuoles, and very numerous non-contractile vacuoles. A siliceous 

 skeleton sometimes present. Cyst- and spore-formation may take place. 

 Actinosphserium and Actiiiophrys sol, sun animalcule, without 

 skeleton. Raphidiophrys, with loose tangential spicules. Acantho- 

 cystis, with radial spicules. Clathrulina, stalked, and with perforated 

 spherical shell. Lead on to 



Order 7. Radiolaria. Marine Rhizopods of globular or conical shape, 

 with differentiated protoplasmic body. Radiating filamentous pseudo- 

 podia, central nucleus-containing capsule, and (generally) a radial or 

 tangential skeleton of silica or acanthin. No contractile vacuole. Re- 

 production by fission or swarm-spores. Parasitic (?) or symbiotic (?) 

 yellow corpuscles very generally present. Actinomma. Thalassicolla, 

 no skeleton. Collozoum, colonial and without skeleton. Acantho- 

 metra. Eucyrtidium, 



