D1FFLUGJA BACILLAKIARUM. 



27 



D. Solowetzkii, however, which is given by Meresch- 

 kowsky in 'Arch. f. mikr. Anat.' XVI (1878), t. x, f. 17, 

 represents a test perfectly symmetrical, with a conical 

 crown (no posterior tube), thickly incrusted with sand- 

 grains, and entirely opaque. It is contracted below as 

 in D. bacillariarum var. elegans, and the lips of the 

 dilated orifice are recurved, and rough with adhering 

 sand-grains, the basal outline being convex. 



Judging 



46 



47 



FIGS. 40 AMP 47. Difflugia bacillariarum. After G. S. West (as D. 

 acuminata var. elegans). Fig. 46 from Wicken Fen, Cambs. x 340. 

 Fig. 47 from Llyn-y-cwm-ffynon, N. Wales, x 520. 



from the figures (we have had no opportunity of 

 examining the actual tests), this and Penard's D. elegans 

 var. teres (' Sarc. des grands Lacs' [1905] p. 16) seem 

 to be identical. No example which could safely be 

 referred to either of these forms has yet been met with 

 in Britain. They would rank under this classification 

 as D. bacillariarum var. Solowetzkii* 



* [It seems probable, however, that Penard's var. teres is a distinct 

 variety more nearly related to var. elegans than to var. Solowetzkii (see figs. 

 48-50).] 



