228 THE OCEAN WORLD. 



their branches, whence the polyps issue, being enlarged into a bell-like 

 shape, whence their name. 0. dichotoma is at once the most delicate 

 and most elegant of the species. It presents a brownish stem, thin 

 as a thread of silk, but strong and elastic. The polyps are numerous : 

 upon a tree eight or nine inches high there may be as many hundreds. 

 C. volubilis is a minute microscopic species, living parasitically on 

 corallines, seaweed, and shelled animals. The stem is a capillary 

 corneous tube, which creeps and twists itself upon its support, throwing 

 out at alternate intervals a long slender stalk, twisted throughout or 

 only partially, which supports a bell-shaped cup of perfect trans- 

 parency, and prettily serrated round the brim. Dr. Johnston found 

 the antennae of a crab so profusely infested with them as to resemble 

 hairy brushes. It is furnished, according to Hassall, with a delicate 

 joint or hinge at the base of each little cup a contrivance designed, 

 it is imagined, to enable the frail zoophyte the better to elude the 

 rude contact of the element in which it lives, by allowing it to bend 

 to a force which it cannot resist. 



The Campanulariae increase by budding, the buds being found in 

 much the same manner as in the Hydrse. It is a simple excrescence, 

 which, in due time, takes the form of the branch from which it 

 proceeds. These buds have their birth at certain distances, and form 

 a new polyp. 



SlPHONOPHORA. 



Alongside the Medusae naturalists place certain marine zoophytes 

 which are equally remarkable for their beauty and for their curious 

 structure, the latter being so complicated that their true organization 

 Ipng remained unknown. They were known, until very recently, 

 under the designation of Hydrostatic Acalephae, or Hydra-medusae. 

 They are known in our days as Siphonophorae. These inhabitants of 

 the deep are graceful in form, and are distinguished by their delicate 

 tissues and brilliant colours. Essentially swimmers, supported by 

 one or many vessels filled with air true swimming-bladders, more or 

 less numerous, and of variable form : they float upon the waves, 

 remaining always on the surface, whatever may be the state of the 

 sea. They are natural skiffs, and quite incapable of immersion. The 

 Siphonophorae form four orders or families ; namely, the Dipliydse, 



