CORDYLOPHORA. 15 



change consists in an increase of the number of arms, 

 which are scattered over the body as in Clava. 



Hab. In the Solent and around the Isle of Wight, not 

 uncommon : the West Bay of Portland (Forbes) : Tenby 

 (Dr. J. F. Davis); Ilfracombe (Gosse): Queensferry, Firth 

 of Forth (T. S. W.). 



Genus CORDYLOPHORA, Allman. 



Der. Kop3u\?), a club, and ^optw, I bear. 

 SYNCORYNA, Agassiz, N. H. U. S. iv. 339. 



GENERIC CHARACTER. Stem well-developed, branching, 

 rooted by a filiform stolon ; the whole of the ccenosarc in- 

 vested by a chitinous polypary ; polypites fusiform, deve- 

 loped from the extremities of the branches, with scattered 

 filiform tentacula : reproduction by means affixed sporosacs, 

 borne on the stem, never on the polypite. 



THE genus Cordylophora is peculiarly interesting, as con- 

 taining the only composite Hydroids that have been found 

 in fresh water. It seems, however, to be equally at home 

 in brackish water. The C. albicola (Kirchenpauer) grows 

 on buoys at the mouth of the Elbe ; and Lindstrom. has 

 obtained C. lacustris in the half-saline waters of the Baltic 

 amidst a curious assemblage of marine and fluviatile 

 plants and animals. In this locality it grows on the stems 

 of Myriophylla. Paludina impura, fresh-water Entomos- 

 traca, and the larvre of insects abound. Associated with 

 these is the Corophium longicorne, an undoubtedly littoral 

 form, while the Tergipes lacinulatus, a thoroughly marine 

 Crustacean, creeps in numbers amongst the branches of 

 the Cordylophora*. 



* Vide a paper by Lindstrom on "the Invertebrate Fauna of the Baltic," 

 in iho ' (Efversigt af Kongl. Vetensk.-Akad. Forhandlingar ' for 18f>5. 



