22 



BRITISH FRESHWATER ItHIZOPODA. 



Dimensions variable ; lengtli from about 100 ^ up to 

 300 ju,, or more : breadth 35-95 fx. 



In the ooze of sands and in marshy ground, usually 

 associated with D. oblonga Bhrenb., and nearly as 

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

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

 HojjJvinsoii). 



This species is about as variable as D. ohionga 



42 



44 



Fiaa. 42-44.— Difflugia acuminata Ehrenb. showing great variation. 

 X 200. Fig. 42.— From pond at Chipperfield, Herts. Fig. 43.— 

 After Ehrenberg, loc. cit. (reduced). Fig. 44. — Var. acaulis Perty. 

 After Perty, loc. cit. 



Bhrenb. 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. 



