40 BRITISH FRESHWATER HELIOZOA. 



less; nucleus placed eccentrically, more or less pyriform, 

 containing a single large nucleolus ; several contractile 

 vesicles ; pseudopodia numerous, long, graiiuliferous, 

 their axes arising from a central granule ; habit solitary. 

 Diameter of body 50 /x to 60 /x ; diameter of nucleus 

 12 n to 15 /A in greatest width ; spicules 20 p. in length. 



Habitat. Aquatic vegetation in lakes and pools,' etc. 



Distribution. ENGLAND. Kinderscout, Derbyshire ; 

 Sheffield district, W. Yorkshire (Brown). 

 WALES. Llyn Idwal, N. Wales (West). 

 SCOTLAND. Cairn well; Aberfoyle (Brown). 

 IRELAND. ? Wicklow (Archer). 



This species has not been recorded as found in 

 colonies. The plasma contains only food particles and 

 numerous granules without living green algal cells. 



The nucleus is pyriform in shape as in the genus 

 Acanthocystis and placed with the smaller end pointing 

 inwards. 



The spicules are straight or irregularly curved with 

 pointed ends and lenticular or linear in broad view ; 

 they are characteristic of the species, and extend as a 

 thin covering for a considerable distance along the 

 pseudopodia. 



West's identification of the forms found by him is 

 somewhat uncertain as they only measured 42 p in 

 diameter and contained numerous " chlorophyll bodies 

 (zoochlorellids ?) " ; he does not give the form of the 

 spicules. Penard thinks his record may refer to R~ 

 ambigua Penard, -which measures 30 /x to 40 /x in 

 diameter. 



R. pallida is a somewhat rare species. 



Genus 6. POMPHOLYXOPHRYS Archer. 



Pompholyxophrys ARCHER Qrt. Jrn. Micr. Sci. (N.S.) IX, 



1869, p. 386. 

 Hyalolampe G-UKEFF Arcli. iniki-. Anat. V, 1869, p. 501. 



Body spherical ; outer envelope of small, colourless 



