54 BRITISH FRKSHWATEH RHIZOPODA. 



4. Cryptodifflugia sacculus Penard. 

 (Plate LX, fig. 17.) 



Cryptodifflugia sacculus 



PENARD Faune Rhiz. Leman (1902), pp. 429-430, 6 figs. ; Sarcodines 



in Cat. Invert. Suisse (1905). p. 83. 

 WAILES & PENARD in Proc. R. Irish Acad. XXXI, LXV (1911), pp. 9, 



16, 25, pi. i, f . 5 a. 

 WAILES 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 p.; diameter 15-22 /A; aperture 6-12 /A. 



Habitat. Aquatic vegetation. 



ENGLAND. Lindal, Westmorland ; Pilmoor and Gor- 

 mire, N. Yorkshire ; New Forest, Hants ; Grimspound, 

 Devon ; Lizard, Cornwall. 



SCOTLAND. Shetland Isles; Outer Hebrides; Scourie, 

 Sutherland. 



IRELAND. Clare Island, Mayo ; Oughterard, Galway. 



Most of the above records are from material collected 

 by W. West. Clare Island arid 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 Pseudodifflugia fascicularis, but the aperture of the 

 latter is usually more thickly encrusted with foreign 

 particles. 



