42 BRITISH FRESHWATER HELIOZOA. 



cally, containing one or sometimes two nucleoli ; con- 

 tractile vesicles absent ; pseudopodia acicular, tenuous, 

 very finely granuliferous ; habit solitary, active. 



Diameter of body usually 25 jn to 30 ^a but may 

 attain 36 iu. 



Diameter of outer envelope 5 /x, to 1 /i, larger than 

 that of the body. 



Spherules in outer investment 2 /a to 4 /a in diameter. 



Habitat.- — Moorland pools. 



Distrihntlon. — England. — Tsle of Wight (Brown). 

 Bpping Forest, Essex (Cash). 



Scotland. — Isle of May (^JBroini). 



Ireland. — Wicklow ; Co. Cork ; Kerry ; Westmeath 

 {Archer, " Scanty but not unfrequently encountered.") 



The spherules which surround the body are appa- 

 rently of a silicious nature and secreted by the ecto- 

 plasm ; they are hollow and unaffected by boiling 

 sulphuric acid, which, however, caused bubbles of gas 

 to form in their interior, showing that they are porous 

 although no apertures could be detected (Penard). 



Archer (whose description of this species was 

 published two weeks previous to that by Greeff) 

 thought the spherules consisted of a protoplasmic 

 material but pointed oat that they were easily detach- 

 able ; Grreeff, under the name of Hijalolawpe fenviitra., 

 described this species as having spherules formed of 

 silica but asserted they were cemented together, inter- 

 stices being left for the protrusion of the pseudopodia. 



A considerable amount of controversy has taken 

 place (.lue to the nearly simultaneous piiblication of, 

 and discrepancies in, the descriptions of the two 

 authors. 



P. ■puii.icea- is one of the most active of the Heliozoa, 

 its comparatively rapid progression being effected by 

 means of its pseudopodia by which it achieves a rolling 

 motion ; as in all members of this genus, they are of 

 extreme tenuity and require careful illumination for 

 their exiunination. 



