78 BRITISH FRESHWATER EHIZOPODA. 



England. — Pilmoor, N. Yorkshire; Oheshire (Gash) ; 

 Wicken Fen, Cambridgeshire (West). 



Ireland. — Clare Island, Mayo. 



The discs forming the tests of this variety have, up 

 to the present, been found arranged only as figs. 140 b 

 and 142 a ; in all cases they were 2 ju, in diameter and 

 when arranged as in fig. 142 a were S/^from centre to 

 centre. The test is in shape very similar to that of G. 

 trochus var. palustris, but its structure is quite different, 

 as it is composed of discs and not of imbricated scales. 



Var. major Penard. (PL XL VI, figs. 6 and 6, and 

 figs. 145 b, 146, and 147 in text.) 



Cyphoderia margaritacea var. major 

 Penard in Mem. Soc. Geneve, XXXI, i, ii (1890), p. 175, pi. viii, 

 fE. 65-67. 

 Cyphoderia ampulla var. major 

 Wailes & Penard in Proo. Roy. Irish Acad. XXXI, lxv (1911), 



pp. 27, 28, 30-31, pi. i, f . 8, pi. ii, f . 10. 

 Wailes in Trans. Liverp. Biol. Soc. XXVI (1912), p. 20 ; in Natu- 

 ralist, 1913, p. 147. 



Test with hemispherical or slightly flattened fundus 

 and short neck, composed of circular discs on a thin 

 chitinous pellicle, each disc surrounded by circular or 

 oval markings disposed in a regular order ; nucleus 

 larger than in the type; plasma and pseudopodia 

 normal. 



Length 80-1 90 /x.; diameter 36-67 /x.; aperture 13- 

 23 fji. 



Habitat. — Sphagnum, mosses, and aquatic vegetation. 



England.— Port Erin, Isle of Man; Oldstead, N. 

 Yorkshire ; Flitwick, Bedfordshire. 



Ireland. — Inishbofin, Gralway. 



First found by Penard in the deep waters of the 

 Lake of Geneva, in a large form averaging 220 fi in 

 length (varying from 180 to 265 /x). The Swiss and 

 British examples found in sphagnum (Flitwick), in 

 moss on dripping rocks (Port Erin), and amongst 

 aquatic vegetation (lake on Inishbofin), are smaller and 

 tend to show that the deep-water form, as indeed 



