TESTACEA 



387 



P. vas (Leidy) (Fig. 181, h). Round or ovoid test; constriction 

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

 ture terminal; 125-170/i 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. 181. a, Plagiojnjxis callida, X200 (Wailes); b, Pontigulasia vas 

 X200 (Cash); c, Phryganella acropodia, Xl90 (Cash); d, Bullinula 

 indica, Xl30 (Wailes); e, f, Heleopera petricola, Xl90 (Cash); g, Nadi- 

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

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

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

 Clypeolina niarginata, 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. 



