434 MOLLUSCA. 



are Alveolaria and Fascicularia, both found in the so-called 

 "White Crag" or "Coralline Crag" (Pliocene), a famous 

 depot of fossil Polyzoa. In the latter (fig. 273) the ccence- 

 cium is globose and often of large size, the cell-tubes being 

 arranged in distinct bundles, which radiate from the centre 

 of the base in all directions, or may be disposed in vertical 

 convoluted laminae. 



