120 BRITISH FRESHWATER EHIZOPODA. 



length ; few larger than this were recorded ; Penard 

 gives 17 to 71 p, as the limits of length, remarking that 

 individuals over 50 /A are rare. 



Small individuals sometimes occur with compara- 

 tively-smooth tests, and the collar may be a well- 

 defined beading around the aperture. 



The enlarged aperture with its collar of quartz-grains 

 renders this species easily recognizable among the 

 Pseudodijfflugise. The test resembles that of Ci*ypto- 

 difflugia sacculus Pen. (length 20 to 40ft) from which 

 species, however, it is distinguished by the longer neck 

 and more prominent collar around the aperture. When 

 active -it is easily identified by the character of the 

 pseudopodia. 



5. Pseudodifflugia archeri Penard. 

 (Plate XL VIII, fig. 23 ; and fig. 154 in text.) 



Pseudodifflugia amphora 

 PENARD (pars) in Rev. Suisse Zool. YII (1899), pp. 80-82, pi. viii. 



ff. 1-5. 

 Pseudodifflugia archeri 



PENARD in Rev. Suisse Zool. IX (1901), pp. 231, 234, 238 ; Faune 



Rhiz. Leman (1902), pp. 456-458, 4 figs.; Sarcodines grands Lacs 



(1905), pp. 57-59, 110, 115, 119, 125, 2 figs, on p. 58 ; Sarcodines in 



Cat. Invert. Suisse (1905), p. 92 ; in Rev. Suisse Zool. XVI (1908), 



pp. 462, 466. 

 AVERINTZEFF in Trudui S.-Peterb. Obshch. XXXVI, n (1906), pp. 



278-279. 



MONTI in Ann. Biol. lacustre, I (1906), pp. 130, 166. 

 ScHOUTEDriN in Ann. Biol. lacustre, I (1906), p. 364, f . 35. 

 DOFLEIN in Sitzb. Ges. Morpb. Miinchen, XXIII (1908), pp. 118-122, 



ff. 2-5. 



WAILES & PENARD in Proc. R. Irish Acad. XXXI, LXV (1911), p. 19. 

 WAILES in Jm. Linn. Soc., Zool. XXXII (1912), p. 126. 



Test moderately large, of a dark colour, oviform, 

 covered with several layers of silicious grains ; trans- 

 verse section circular or broadly oval ; aperture ter- 

 minal, circular ; plasma grey, granular, often containing 

 numerous small crystals; nucleus placed posteriorly, 

 large, granular, containing several nucleoles ; several 

 contractile vesicles and many vacuoles usually present; 

 pseudopodia long, numerous, straight or forked. 



