THE SARCODINA 



75 



spindles, or blade-shaped plates, and may become firmly attached 

 to one another, forming latticed skeletons, like those of Radiolaria 

 {Clathrulina, Fig. 39). Intermediate stages are seen in such forms 

 as Diplocystis, where the plates are very small and arranged without 



Pig. 39. Clathrulina elegans Cienk. [GREEFF.] 



any apparent order in the gelatinous mantle. In Raphidiophrys 

 (Fig. 40) the silicious plates are much larger and more regularly 

 arranged, while in Pinaciophora and Acanthocystis (B, C, D} they be- 

 come so closely knit that they form an efficient shield. In Acantho- 

 cystis, each plate is a small rectangular prism, laid tangential to the 

 surface with sharper spicules arranged at intervals at right angles to 



