ASTIiODISCULL'S RADrANS. 27 



adhering to it ; ectoplasm merging gradually into tlae 

 endoplasm and more or less loaded witli granules of a 

 green, yellow or brown colour ; pseudopodia attenuate, 

 straight, not granulif erous, of moderate length. ; nucleus 

 not large, placed eccentrically; a single contractile 

 vesicle usually present. 



Diameter of body 13 /x to 17 ju, (Penard) ; 25 f^ 

 {West). Diameter of mucilaginous investment about 

 twice that of the body. 



Habitat. — Pools and ditches. 



Distribution. — England. — Brigg, Lincolnshire 

 {West). 



Scotland. — Inverary {Broivn). 



Some of the pseudopodial axes frequently do not 

 project beyond the mucilaginous zone, and it is pro- 

 bably to these that Greeff refers when he speaks of 

 spicules being imbedded in the outer envelope. 



Heliophrys varians (Schulze) as described by West 

 (1901) is undoubtedly an Astrodlsculus, and differs 

 from A. radians only in its slightly larger size and the 

 branching of some of the pseudopodia. 



Heterophrys varians Schulze and Heliophrys variabilis 

 Grreeff appear to be Nuclearia and not identical Avith 

 A. radians. 



Sub-order III. CHALAROTHORACil Hertwi^ & 



Lesser. 



b 



Heliozoa having an external envelope composed of 

 solid elements with or without a matrix of plasma. 



Synopsis of the Freshwater Genera. 



(a) Envelope consisting of a thick layer of plasm'a contain- 



in^"— 



Chitinous spicules. (4) Heterophrys. 



Silicious spicules. (5) Raphidiophrys. 



Spicules of special forms. Raphiilocystiii. 



