DIVISIONS OF THE HYDEOZOA. 



63 



bell-shaped disc, which is attached by its base to the parent organ- 

 ism, and has its cavity turned outwards. From the roof of this 

 disc there is suspended a kind of handle, which corresponds to the 

 clapper of the bell, and is termed the "manubrium" (Lat. for 

 handle). From the fixed or proximal extremity of the central 

 process or manubrium proceed four or eight canals, which extend 

 to the margin of the bell, where they all open into a circular canal 



Fig. 32. — Group of zooids of Hydractinia echitiata. Enlarged (after Hincks). a a Nu- 

 tritive zooids ; & & Generative zooids, carrying sacs filled with ova (" .sporosaca "). 



surrounding the mouth of the bell. This bell-shaped reproductive 

 bud may attain no higher development than this, and may remain 

 permanently attached to the parent organism from which it is pro- 

 duced. In other cases, however, a higher state of development is 

 reached. The generative bud or gonophore (fig. 29, C) becomes 

 detached from its parent colony ; the manubrium or central process 

 develops a mouth at its free or distal extremity ; the mouth of the 



