PSEUDODIFFLUGIA AECHERI. ]21 



Length 55-110 /z (Penard gives 50-170 /A as the 

 limits of length and 80-100 /x as the usual size). 



Habitat. Deep lakes and aquatic vegetation. 



ENGLAND. Shrewsbury, Shropshire ; Devonshire ; 

 Cornwall. 



WALES. Bodelwyddan, Flintshire. 

 IRELAND. Clare Island and Koonah, Mayo. 



The test is characterized by its thick covering of 

 amorphous silicious particles arranged like a mosaic in 

 the cementing medium, each small particle being 

 isolated from its neighbours. 



FIG. 154 Pseudodifflugia archeri. x 200. 



The crystals found in the plasma are considered by 

 Penard to consist of some organic compound ; owing 

 to the opacity of the test the contents are not visible 

 unless the specimen is immersed in oil of cloves or 

 Canada balsam. The plasma and contractile vesicles, 

 etc., cannot be studied in the living animal unless they 

 happen to be protruded from the aperture. 



5. Pseudodifflugia compressa (Schulze) Penard. 

 (Plate LII, figs. 9-11.) 



Pleurophrys compressa 



SCHULZE in Arch. mikr. Anat. XI (1875), p. 125, pi. vii, ff. 4, 5. 

 ARCHER in Qrt. Jrn. Micr. Sci. (N. s.) "VII, p. 204, pi. xiii, ff. 9, 96 ; 



in Proc. Dubl. Micr. Club, III, 3 (1880), pp. 273-274, pi. x, ff. 9a, 96. 

 Pseudodiffluyia compressa 

 PENARD Faune Rhiz. Leman (1902), pp. 458-459, 2 figs. ; Sarcodines 



in Cat. Invert, Suisse (1905), p. 93. 

 AVERINTZEFF in Trudui S.-Peterb. Obslich. XXXYI, 11 (1906), 



p. 275. 



SCHOUTEDEN in Ann. Biol. lacustre, I (1906), pp. 363, 364. 

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



p. 19. 



