18 BBITISH FRESHWATER RHIZOPODA. 



thickly incrnsted with diatom-frustules as to leave little 

 or none of the natural surface of the chitinous test 

 visible. The frustules were destitute of colouring 

 matter. 



6. Difflugia pristis Penard. 

 (Plate XVIII, figs. 9-11.) 



Difflugia fallax PENARD (pars) in Mem. Soc. Geneve, XXXI 



(1890), 2, p. 144, t. iv, ff. 45-51 ? 

 Difflugia pristis PENARD Faune Rhiz. Leman (1902), p. 254, 



if. 1-7 ; AVERINTZEV in Trudui S.-Peterb. Obshch. XXXVI 



(1906), 2, p. 208; SCHOUTEDEN in Ann. Biol. Lacustre, 



1,3 (1906), pp. 344,347. 



Test ovoid, very regular, variable in length, which 

 is generally about equal to twice the breadth ; the 

 mouth contracted, terminal, and relatively small. 

 Pseudopodia thin, numerous, mobile, not branching. 



Dimensions : Length 60-65 p ; breadth 30-35 /x. 



On submerged vegetation, Hill Cliff reservoir, near 

 Warrington. Loch Ness, Scotland (D. J. Scour field). 



This organism agrees with Penard's description in 

 * Faune Rhizopodique du Bassin du Leman ' except in 

 one respect, namely, that instead of being " blackish " 

 and opaque, the tests of all the individuals we 

 examined from the Hill Cliff locality were mem- 

 branous, carrying on their exterior a few scattered 

 sand-grains mixed with thin scale-like particles, and 

 not so dense as to prevent the plasma from being 

 distinctly seen. This may have been caused by their 

 living amongst floating vegetation in clear water, and 

 not on the muddy bottom. Having regard to the 

 dimensions of the organism, and the character and 

 movements of the pseudopodia, they could not be 

 referred to any other species than D. pristis Penard. 



7. Difflugia petricola sp. nov. 

 (Plate XIX, figs. 5-7.) 



Test spherical, with a short, cylindrical, or slightly- 

 swollen neck ; incrusted with large angular sand- 



