22 



BRITISH FRESHWATER RHIZOPODA . 



Dimensions variable ; length from about 100 /x up to 

 300 /x, or more : breadth 35-95 fi. 



In the ooze of sands and in marshy ground, usually 

 associated with I), oblonga Ehrenb., and nearly as 

 common. Glyder Fach, N. Wales, up to 2200 ft, 

 (G. 8. West). Moel Siabod, N. Wales, at 2500 ft. (J. 

 Hopkinson) . 



This species is about as variable as D. oblonga 



42 



FIGS. 42-44. Diftlugia acuminata Ehrenb. showing great variation, 

 x 200. Fig. 42. From pond at Chipperfield, Herts. Fig. 43. 

 After Ehrenberg, loc. cit. (reduced). Fig. 4i. Var. acaulis Perty. 

 After Perty, loc. cit. 



Ehrenb. Ehrenberg's name was given to the common 

 large form, which has a nearly cylindrical test, slightly 

 enlarged posteriorly, and is three to four times longer 

 than broad, with an acute apex. Between this which 

 may be regarded as typical and the smaller varieties, 

 there is a large gradation of forms, some with two or 

 more points. The dimensions of these abnormal forms, 

 which can hardly be regarded as permanent varieties, 

 vary considerably. 



