Fig. 13.— Shells and tests. [A, SCHEWIAKOFF; B, ORIGINAL; C, Butschli; D, STEIN.] 

 A. Euglypha alveolata Duj. The shell consists of oval siliceous plates glued together by a sili- 

 ceous (?) cement. B. Cockliopodium digitatum, n. sp. The test is membranous and perforated 

 for pseudopodia. C. Pseudochlamys patella Clp. and Lach. The test is membranous and shield- 

 like. D. Ceratium tripos Nitsch. The shell consists of cellulose plates of diverse size and shape. 



