30 BRITISH FRESHWATER HELIOZOA. 



SYNOPSIS OF THE BRITISH SPECIES. 



Usually of a green colour ; no contractile vesicle normally 

 present; diameter about 70 /t. (I) H. myriopoda. 



Green corpuscles usually absent; several contractile vesicles 

 usually present ; diameter of body about 22 /n. 



(2) H.focfoi. 



No contractile vesicles usually present ; outer envelope 

 finely fimbriated; diameter of body about 21 /u. 



(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, 

 I'etractile. Diameter 11 p. to 15 /<. 



1. Heterophrys myriopoda Archer. 

 (Plate LXVIII, figs. 1 and 2.) 



Heteroplinjs m yriopoda 



ARCHER Qrt. Jrn. Micr. Sci. (N.S.) IX, 1869, p. 267, pi. xvii, f. 4. 



PEXARD Heliozoaires, 1904, p. 149, figs. 

 H. iiwn'ini 



HERTWIG & LESSER Arch. mikr. Anat. X, 1874, Suppl., p. 213, pi. iv. 



f. 4. 

 ? Acanthocystis tenuispina 



ZACHARIAS Forsclmngsber. Plon III, 1895, p. 73, pi. i, f. 4. 



Body spherical ; outer envelope thick, mucilaginous, 

 closely beset with numerous fine, chitinous spicules 

 partially embedded in it; endoplasm differentiated 

 from the ectoplasm and placed eccentrically ; ecto- 

 ])!.-ism usually crowded with spherical green alga? 

 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 ^ to 64 ^ (Penard) ; 65 /u to 

 80 [ji (Archer). Outer zone 10 /A to 15 //, thick. 



HaMtat. Moorland pools and marshes. 



