54 BRITISH FRESHWATER RHIZOPODA. 
4. Cryptodifflugia sacculus Penard. 
(Plate LX, fig. 17.) 
Cryptodifiugia sacculus 
PrnarD Faune Rhiz. Léman (1902), pp. 429-480, 6 figs.; Sarcodinés 
in Cat. Invert. Suisse (1905), p. 83. 
Wares & PEnarp in Proc. R. Irish Acad. KXXI, txv (1911), pp. 9, 
16, 25, pl. i, f. 5a. 
WaliLezs in Naturalist, 1913, p. 146. 
Test small, pyriform, not compressed, hyaline or 
yellowish in colour, composed of a homogeneous, 
chitinous, transparent membrane usually covered with 
adherent foreign particles and sometimes diatoms; 
aperture circular, terminal, usually enlarged; plasma 
colourless, granular; nucleus single with a central 
nucleole; one or two contractile vesicles usually 
present; pseudopodia few in number, of moderate 
length, pointed. . 
Length 20-30 »; diameter 15-22 ; aperture 6-12 p. 
Halitat.—Aquatic vegetation. 
Encauanp.—Lindal, Westmorland; Pilmoor and Gor- 
mire, N. Yorkshire; New Forest, Hants; Grimspound, 
Devon; Lizard, Cornwall. 
~ Scornanp.—Shetland Isles; Outer Hebrides; Scourie, 
Sutherland. 
Trevanp.—Clare Island, Mayo; Oughterard, Galway. 
Most of the above records are from material collected 
by W. West. Clare Island.and Pilmoor each provided 
a single individual with a smooth colourless test and 
unenlarged aperture; the plasma appeared normal. 
The test of this species resembles small forms of that 
of Pseudodifiugia fascicularis, but the aperture of the 
latter is usually more thickly encrusted with foreign 
particles. 
