io8 



THE RADIOLARIA 



It contains a peculiar cone of doubtful significance (Fig. 5, B, p). 

 The ectoplasm streams out from the capsular pore-plate and forms a 

 dense bubbly mass around this opening. From this point it passes 

 as a thin layer around the capsule, so that the cytoplasm is asym- 

 metrically distributed. These Radiolaria are, in fact, bilaterally 

 symmetrical. Lateral outgrowths from the spicule or sagittal ring 

 give rise to a helmet-like shell or "cephalis," in the upper part 



FIG. 0. 



Eucyrtidium cranioides, Haeck., x 150; one of the Monopylaria. Entire animal as seen in 

 the living condition. The central capsule is hidden by the beehive-shaped siliceous shell 

 withinlwhich it is lodged. 



of which the central capsule is lodged. The cephalis becomes 

 voluminous and often constricted, producing a vast array of specific, 

 skeletal variety, the whole of which is produced by modification of 

 a single spicule. The nucleus, though often lobed, remains single. 

 Spore-formation is known to occur, but no form of reproduction has 

 been adequately investigated. The bionomics of the group are 

 quite unknown. 



The Tripylaria or Phaeodaria form another large group, most 



