30 british freshwater heliozoa. 



Synopsis op the British Species. 



Usually of a green colour ; no contractile vesicle normally 

 present; diameter about 70 (U. (1) E. myriopoda. 



Green corpuscles usually absent ; several contractile vesicles 

 usually present ; diameter of body about 22 yu. 



(2) H.fookei. 

 No contractile vesicles usually present ; outer envelope 

 finely fimbriated; diameter of body about 21 fi. 



(3) H. radiata. 



The fourth species belonging to this genus has not been 

 recorded from the British Isles ; its description is as follows : 

 H. glabrescens Pen. Of small size; outer mucilaginous 

 envelope rudimentary or invisible ; numerous long radial 

 spines present which are invisible in the living animal but 

 apparent in a dry state; pseudopodia long, granuliferous, 

 retractile. Diameter 11 ju to \b fi. 



1. Heterophrys myriopoda Archer. 

 (Plate LXVIII, figs. 1 and 2.) 



Heterophrys myriopoda 



Abcheb Qrt. Jrn. Micr. Sci. {n.s.) IX, 1869, p. 267, pi. xvii, f. 4. 



Penaed Heliozoaires, 1904, p. 149, figs. 

 H. marina 



Hbktwig & Lessee Arch. mikr. Anat. X, 1874, SuppL, p. 213, pi. iv, 

 f. 4. 

 .'' Acanthocystis tenuispina 



ZACHA.EIAS Porsohungsber. Plon III, 1895, p. 73, pi. i, f. 4. 



Body spherical ; outer eiivelope thick, mucilaginous, 

 closely beset with numerous fine, chitinous spicules 

 partially embedded in it; endoplasm differentiated 

 from the ectoplasm and placed eccentrically ; ecto- 

 plasm usuall}'" crowded with spherical green algae 

 living in symbiosis ; nucleus single, placed eccen- 

 trically ; central granule present ; pseudopodia 

 numerous, long, tapering, finely granuliferous, their 

 axes arising from the central granule; pulsating 

 vesicle usually absent. 



Diameter of body 50 /x. to 64 ju, (Penard) ; 65 /x to 

 80 /A (Archer). Outer zone 10/x, to 15 /a thick. 



Habitat. — Moorland pools and marshes. 



