TESTACEA 



485 



deep and well-marked; with sand-grains and other particles; aper- 

 ture terminal; 125-170/z long; fresh water ponds. Stump (1943) 

 made a study of the nuclear division of the organism. During meta- 

 phase 8-12 "chromosomes" form a well-defined equatorial plate; 

 average time for completion of the division was found to be 80 min- 

 utes. 



Fig. 205. a, Plagiopyxis callida, X200 (Wailes); b, Pontigulasia vas 

 X200 (Cash); c, Phnjganella acropodia, X190 (Cash); d, Bullinula 

 indica, X130 (Wailes); e, f, Heleopera petricola, X190 (Cash); g, Nadi- 

 nella tenella, X400 (Penard); h, Frenzelina reniformis, X600 (Penard); 

 i, Amphitrema flavum, X360 (Cash and Wailes); j, Pseudodifflugia gracilis, 

 X330 (Cash); k, Diaphoropodon mobile, X270 (Cash and Wailes); 1, m, 

 Clypeolina marginata, X330 (Cash and Wailes). 



Genus Phryganella Penard. Test spheroidal or ovoid, with sand- 

 grains and minute diatom shells; aperture terminal, round; pseudo- 

 podia drawn out to a point; fresh water. 



P. acropodia (Hertwig and Lesser) (Fig. 205, c). Test circular in 



