32 BRITISH FRESHWATER RH1ZOPODA. 



narrow mouth, not less than by the absence of large 

 sand-grains. The chief variability consists in the 

 sometimes rounded, sometimes bluntly- conical crown. 

 The siliceous scales covering the test are glistening and 

 transparent. From D. oblonga var. venusta the species 

 is likewise easily differentiated, the lower part of the 

 test being, as the figures show, destitute of a neck, 

 though the two organisms exist side by side in the 

 same ponds, and not infrequently in the same drop of 

 water. 



12. Difflugia lucida Penard. 

 (Plate XXI, figs. 3 and 4.) 



Difflugia lucida PENARD in Mem. Soc. Geneve, XXXI (1890), 

 2, p. 145, t. iv, ff. 52-58; Faune Khiz. Leman (1902), p. 

 273, ff. 1-5 (p. 274) ; in Jahrb. nassau. Ver. Naturk. 

 XLIII (1890), p. 70; and in Arch. Protist. II (1903), p. 

 256 ; AVERINTZEV in Trudui S.-Peterb. Obshch. XXXVI 

 (1906), 2, p. 187 ; SCHROUTEDEN in Ann. Biol. Lacustre, 

 I, 3 (1906), pp. 342, 345. 



Test thin, chitinous, transparent, covered with 

 variously-sized, angular, siliceous scales, very trans- 

 parent, a ring of these scales generally surrounding 

 the mouth ; much compressed, the width in narrow 

 lateral view hardly exceeding a third of the broader 

 surface ; in broad view uniformly arched, the sides 

 straight, and sometimes nearly parallel from each 

 cusp of the crown down to the truncated mouth. The 

 body of the animal, which is visible through the trans- 

 parent walls of the test, not occupying the whole of 

 the cavity, being attached to the f undus by threads of 

 protoplasm ; nucleus normally situated ; pseudopodia 

 few in number, short, and simple. 



Dimensions : Length 60-80 /x ; breadth about 50 /x ; 

 in lateral view, breadth 17-20 JJL. 



In Sphagnum. Near Sutton Broad, Norfolk (E. 

 Gurneif). Towyn, Merionethshire. Midlothian, Scot- 

 land (W. Evans). 



