140 BRITISH FEESHWATEE EHIZOPODA. 



Var. amethystea Penard. (Plate XXIX, fig. 22.) 



Heleopera petricola var. amethystea PENARD in Rev. Suisse 

 Zool. VII, 1 (1899), p. 53, t. v, ff. 1-5; Faune Rhiz. 

 Leman (1902), p. 384, if. 7, 8 (p. 382) ; and Sarc. grands 

 Lacs (1905), p. 36, 2 if. (p. 37) ; AVERINTZEV in Trudui 

 S.-Peterb. Obshch. XXXVI (1906), 2, p. 256; SCHOU- 

 TEDEN in Ann. Biol. Lacustre, I, 3 (1906), p. 357; MURRAY 

 in Pr. R. Phys. Soc. (Edinb.) XVII, 4 (1908), p. 128. 



Larger than the type, compressed laterally, oval- 

 elongate, with an arched crown, the lateral margins 

 straight or slightly convex, the oral extremity also 

 convex, its corners rounded, the mouth thin-lipped, 

 the lips yellowish and separated so as in narrow lateral 

 view to form a notch. The chitinous test covered 

 with comparatively-large thin plates or amorphous 

 scales, which in places are irregularly imbricated ; the 

 whole structure deeply tinged with purple, or what may 

 be described as a pure amethystine tint. The plasma 

 (containing usually one or more contractile vacuoles) 

 only partially filling the cavity of the test; nucleus 

 normally situated ; pseudopodia numerous, simple or 

 branched. 



Dimensions : Length 11 5-120 /*. 



In Sphagnum and amongst aquatic mosses at pond 

 sides ; not infrequent, both in lowland and sub-alpine 

 districts. Dunham, Cheshire ; near Towyn, Llyn Idwal, 

 and in the Sychnant Pass, N. Wales. Near Button 

 Broad, Norfolk (E. Gurney}. Epping Forest, Essex 

 (D. J. Scourfield). Moel Siabod, N. Wales, at 2500 

 feet; Killough, Co. Wicklow, Ireland (/. Hopkinson). 

 Aberfoyle, Scotland (W. Evans}. 



Penard separated this from the type on account of 

 its possessing distinctive characters in regard to size 

 and structure. The colour is a remarkably pure 

 amethystine tint, which, it is thought, may probably be 

 due to the presence of manganese. He remarks that 

 the form may be distinguished from the type not 

 only by the peculiarity of colour but also by its 



