16 BRITISH FRMSHWATER RHIZOPODA. 



the long neck characteristic of that species. The limits 

 of these forms are often difficult to determine. They 

 are very variable. D. Penardi seems sufficiently dis- 

 tinct in its general features to rank as a species. In 

 length it is about half the average measurement of 

 D. oblong a var. lacustris, and it has a narrower mouth. 

 [The small forms of Ehrenberg's Difflugia protei- 

 formis (fig. 41) appear to resemble this species more 

 closely than any other.] 



4. [?] Difflugia pulex Penard. 

 (Plate XVIII, figs. 7 and 8.) 



Difflugia pulex PENARD Faune Rhiz. Leman (1902), p. 229, 

 ff. 1-8 (p. 230) ; AVERLNTZEV in Trudui S.-Peterb. Obshch. 

 XXXVI (1906), 2, p. 196; SCHOUTEDEN in Ann. Biol. 

 Lacustre, I, 3 (1906), pp. 343, 346. 



Test smaller than that of the preceding species, oval, 

 tapering suddenly into a short neck, the mouth trun- 

 cated. Substance of the test thin, semi-transparent 

 and yellowish, or covered with small sand-grains. 

 Pseudopodia variable; the nucleus single, but owing 

 to the opacity of the test usually invisible. 



Dimensions : Length 65-70 fj. ; breadth 40-45 p. 



In similar situations to the preceding. Chelford, 

 Cheshire ; Dolgoch, Merionethshire ; Sychnant Pass, 

 Carnarvonshire. Bricket Wood Common, Herts ; 

 Moel Siabod and Nant Francon, N. Wales ; Calary 

 Bog, Co. Wicklow, Ireland (/. Hopldnson}. 



Examples met with in the above localities correspond 

 with Penard' s description and figures, but they are 

 invariably incrusted with sand-grains or other ex- 

 traneous material, and opaque. We have not met 

 with any showing the yellowish chitinoid test which 

 seems to be a feature of the continental forms. [Those 

 also being much smaller, usually 22-25 fj. and never 

 exceeding 30 /u in length, the identification of the 

 species is doubtful.] 



