118 BRITISH FRESHWATEE RHIZOPODA. 



British Isles the length usually varies from 20 to 26 ju,. 

 Colourless tests occasionally occur. 



3. Pseudodifflugia horrida Penard. 

 (Piate LIT, figs. 1-4.) 



Fseudodifflugia horrida 



Pbnaed Taune Rhiz. Leman (1902), pp. 452-453, 5 figs. ; Sarcodines 



gi-ands Laos (1905), pp. 115, 596, 604-606, 3 figs. ; Sarcodines in Oat. 



Invert. Suisse (1905), p. 91. 

 Mtjrkat in Proc. R. Soc. Edinb. XXV (1905), p. 615. 

 Wailes & Penaed in Proc. R. Irish Acad. XXXI, lxv (1911), p. 19. 



Test of medium size, dark grey or brown in colour,, 

 opaque, oviform, slightly compressed, flexible, especi- 

 ally around the aperture ; covered with a rough coating 

 of foreign particles and projecting diatom-frustules ; 

 aperture terminal, of variable- shape ; the plasma clear, 

 granular, with few inclusions, entirely filling the test; 

 nucleus small, with a single large nucleole ; one or two 

 contractile vesicles usually present ; pseudopodia long, 

 attenviate, straight. 



Length 35-60 ju. ; breadth about three quarters of the 

 length ; aperture about half of the breadth ; thickness 

 about nine tenths of the breadth. 



Habitat. — Aquatic vegetation. 



England. — Cheshire (Gash). 



Scotland. — Loch Ness, Inverness-shire (Penard). 



Ireland. — Inishbofin, Galway. 



Penard noticed that the individuals found in Loch 

 Ness were infested with large numbers of bacteria of 

 very small diameter and about 20 fx in length, similar 

 to, but much more numerous than, those found in the 

 Swiss members of this species ; in addition to these 

 bacteria the majority of the Loch Ness individuals 

 contained parasites in appearance like degenerate 

 Peranema (Duj.) l)ut wanting the flagellum; they 

 were 15 to 20 /.i in length ; their life-history is un- 

 known. Similar parasites are found in the Heliozoon 

 UdjihicliopJirys viritlitt. Ciliates are often seen in the 



