PSEUDODIFFLUCIIA HOEEIDA. 119 



tests of Rhizopoda, but may be only intruders in most 

 cases and not truly parasitical. 



The plasma of P. horrid a can only be examined by 

 expelling it from the test, which is covered by a con- 

 fused mass of diatoms, grains, and silicious plates ; the 

 colour as a whole varies from brown to nearly black ; 

 the aperture appears flexible and may be found entirely 

 closed or widely distended ; its outline is usuall}^ very 

 indistinct. The pseudopodia are rarely observed. 



4. Fseudodifflugia fascicularis Penard. 

 (Plate LII, figs. 5-8.) 



? Fseudodifflugia amphora 



Leidy Freshw. Rhiz. N. Amer. (1879), p. 201, pi. xxx, f.28. 

 Fseudodifflugia fascicularis 



Penaed Faune Rhiz. Leman (1902), pp. 463-455, 5 figs. ; Sarcodincs 

 in Oat. Invert. Suisse (1905), p. 92. 



AVEBINTZEFP in Tmdui S.-Peterb. Obshch. XXXVI, ii (1906), p. 275. 



ScHOTJTBDBiiT in Ann. Biol, lacustre, I (1906), p. 364, f. 34. 



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



Wailbs in Scott. Natur. 1912, pp. 61, 64 ; in Jrn. Linn. Soc, Zool. 

 XXXII (1913), pp. 209, 213; in Naturalist, 1913, p. 148. 



Test variable in size, pyriform, yellowish in colour, 

 not compressed, covered with relatively-large quartz- 

 grains, or occasionally diatom-frustules ; aperture 

 circular, terminal, larger in diameter than the neck 

 and. surrounded by a collar of variously-sized grains ; 

 nucleus large, containing numerous nucleoles ; plasma 

 limpid, granular, partly filling the test; pseudopodia 

 numerous, long, attenuate, straight or forked. 



Length 23-40 /x.; diameter two thirds to three 

 quarters of the length ; aperture about half of the 

 diameter. 



Habitat. — Aquatic vegetation. 



England. — Bedfordshire. 

 Scotland. — Outer Hebrides. 



Ieeland. — Clare Island and Achill Island, Mayo ; 

 Inishbofin, G-alway; Kerry. 



British individuals usually vary from 25 to 35 ju, in 



