ACTINOPODA, HELIOZOA 513 



cylindrical stalk with an enlarged base; small siliceous spicules; 

 nucleus in the base of stalk; multiplication by budding. 



W. borealis M. (Fig. 216, /). About I8O/1 in diameter; stalk often 

 up to 1.1 mm. long; salt water. 



Genus Pinaciophora GreefT. Spherical; outer envelope composed 

 of circular discs, each being perforated with 19 minute pores; cyto- 

 plasm reddish ; fresh water. 



P. fluviatilis G. (Fig. 216, g). Diameter 45-50ju, but somewhat 

 variable; in freshwater ponds. 



Family 8 Clathrulinidae Claus 



Genus Clathrulina Cienkowski. Envelope spherical, homogeneous, 

 with numerous regularly arranged openings; with a stalk; proto- 

 plasm central, not filling the capsule; nucleus central; pseudo podia 

 numerous, straight or forked, granulated ; fresh water. 



C. elegans C. (Fig. 217, a). Envelope colorless to brown, perforated 

 by numerous comparatively large circular or polygonal openings; 1 

 or more contractile vacuoles; nucleus central; diameter 60-90^, 

 openings 6-10m; length of stalk 2-4 times the diameter of envelope, 

 3-4 n wide; solitary or colonial; among vegetation in ponds. Taxon- 

 omy and stalk formation (Valkanov, 1928). 



Genus Hedriocystis Hertwig and Lesser. Envelope spherical, 

 openings minute, surrounded by polyhedral facets or ridges; with 

 stalk; solitary or colonial; fresh water. 



H. reticulata Penard (Fig. 217, b). Envelope colorless or pale 

 yellow, facets regularly polygonal with raised borders; stalk solid, 

 nucleus central; 1 contractile vacuole; each pesudopodium arises 

 from a pore located in the center of a facet; solitary; capsule about 

 25/* in diameter; body about \2y. in diameter; stalk about 70// by 

 1.5/z; in marshy pools. 



Genus Elaster Grimm. Envelope spherical, delicate, penetrated 

 by numerous more or less large pores; without stalk; pseudo podia 

 many, straight filose. 



E. greeffi G. (Fig. 217, c). Diameter of envelope 20/*; envelope 

 delicate, colorless; many pseudopodia; in peaty soil. 



Genus Choanocystis Penard. Spherical envelope with perforations 

 which possess conical borders; openings of cones provided with 

 funnel-like expansions, edges of which nearly touch one another; 

 fresh water. 



C. lepidula P. (Fig. 217, d). Diameter 10-13^; envelope delicate; 

 1 or more contractile vacuoles; pseudopodia very long. 



