160 BRITISH FRESHWATER RH1ZOPODA. 



teriorly, the surface having a mulberry- shaped appear- 

 ance sometimes masked by the sand-grains of irregular 

 size with which it is covered ; the crown spherical, the 

 sides tapering with a convex curve to the aperture which 

 is about one-third the diameter of the test, has a narrow 

 lip or collar, and is hexagonal with sinuous lobes. 

 Plasma occupying about two-thirds the cavity of the 

 test, to which it is attached by numerous slender 

 filaments; usually with a single large contractile 

 vesicle ; nucleus delicate, with numerous nearly circular 

 nucleoli of unequal size ; pseudopodia normal. 



Dimensions: Average diameter 130 p (Penard). 



Ireland, 1867 (W. Archer). 



105 106 



FIGS. 105 AND 106. Difflugia tuberculata : 105, lateral view; 106, oral 

 view. Outlines derived from Wallich's and Penard's figures, x 200. 



As in the case of several other rhizopods which 

 Archer found in Ireland and exhibited before the Dublin 

 Microscopical Club, he omitted to give the locality. 

 That the species does occur in Ireland has recently 

 been confirmed by Dr. Penard. 



Wallich described Diffliigia tuberculata, as of varietal 

 rank only, in the ' Annals of Natural History ' for 

 March, 1867, without giving any locality for it, and 

 in that magazine for the previous January a very 

 similar form from Bombay was described by Carter 

 under the name of Difflugia bombayensis. This is 

 usually considered to be the same species, but was 

 stated by him to have an even aperture which also 

 appears to be without a lip and smaller than that of 

 D. tuberculata, the test not being truncated for it. 



Archer's record has only recently been noticed.] 



