80 BRITISH FRESHWATER RHIZOPODA. 



Three different arrangements of these " perfora- 

 tions " as found in tests from several localities are 

 illustrated in figs. 146 and 147 ; the pattern of fig. 5, 

 PI. XLVI, has a superficial resemblance to the 

 arrangement of the bars on tests of Arcella, vulgaris 

 which are in three sets of parallel lines disposed at 

 angles of 60 apart. 



The nucleus is large, granular, and contains a small 

 number of bluish nucleoles surrounded by hyaline 

 rings. The presence in the plasma of foreign bodies, 

 perhaps urates and crystals of oxalate of lime, as in 

 other members of the genus, has been noticed above. 



FIG. 148. Outlines of tests of Cyphoderia trochus and two varieties, 

 x 240. a, C. trochus (type) ; b, var. palustris ; c, var. amphoralis. 



2. Cyphoderia trochus Penard. 

 Plate XLV, fig. 1, and figs. 148-150 in text.) 



Cyphoderia ampulla 



APSTEIN Siisswasserplankton (1896), p. 153, f. 55. 

 AVERINTZEFF (pars) in Trudui S.-Peterb. Obshcli. XXXVI (1906), 



11, pp. 306, 307. 



SCHOUTEDEN (pars) in Ann. Biol. lacustre, I (1906), pp. 370-371. 

 Cyphoderia trochus 

 PENARD in Rev. Suisse Zool. VII, i (1899), n, pp. 72-75, 106, 115, 



pi. vii, ff. 1-14 ; Faune Rhiz. Leman (1902), pp. 485-488, 10 figs. ; 



Sarcodines grands Lacs (1905), pp. 48-50, 110-123 passim, fig. p. 49; 



Sarcodines in Cat. Invert. Suisse (1905), p. 90; in Rev. Suisse Zool. 



XYI (1908), p. 462. 

 FOREL Le Leman, III (1904), p. 137. 

 ZSCHOKKE in Arch. Hydrobiol. I (1906), p. 4. 

 KOFOID in Bull. Illinois Lab. XYI (1908), p. 103. 

 WAILES & PENARD in Proc. R. Irish Acad. XXXI, LXV (1911), p. 31, 



ff. 11, 14a-c. 



Test conical with mamillate fundus, tapering to- 

 wards the curved neck; composed of circular bi-convex 

 imbricated scales arranged in diagonal rows ; aperture 

 oval, oblique; plasma normal; pseudopodia filiform, 

 long, and straight. 



