PROTOZOA 19 
a stalked genus, has a spherical siliceous shell perforated by 
numerous openings. 
Fra. 14.—A portion of A ctino- 
sphaerium  Kichhornii, 
Ehrb., highly magnified, 
seen in optical section. 
From Bronn. 
1. Nuclei. 
2. Ectoplasm. 
3. Endoplasm. 
4 
. Pseudopodia with axis. 
5. Food mass in food vacuole. 
Fic. 15.—Clathrulina elegans, Cienk. 
x 150-200. From Bronn. 
1. Stalk. 
2. Shell. 
3. Pseudopodia protruding through apertures 
in shell. 
