40- NATURAL HISTORY OF 



seeing the Turris in a state of ovipositing, and he 

 observed frequently the escape of the embryos, but 

 was not successful in rearing them to maturity. Dr. 

 T. S. Wright, however, was subsequently able to keep 

 the embryos until they became perfect hydroids. 



Genus IV. Cordylophora, All. {Kophvkrj, a club, 

 <f)opeo), I bear.) 



Stem well developed, branching. Coenosarc entirely 

 invested by the polypary. Polypites fusiform, at ex- 

 tremities of the branches with scattered j&Iiform teuta- 

 cula. Reproduction by fixed sporosacs borne on the 

 stem.— T. H. 



J. C. LACUSTEis, Allman. Plate II. fig. 4. 



Syncoryne lacustris {Ag.). 



Hab, : Grand Canal Docks, Dublin (All.) ; Commer- 

 cial and West India Docks, London {Dr. BowerhanJc 

 and All.) • Llyn Regis {Dr. Lowe), &c. Height 2 — 8 in. 

 Polypites white, ovoid, supported on a fleshy neck. 

 Number of tentacles 12 — 14, which, like those of 

 Hydra, can be elongated or shortened very remarkably. 



Reproduction by ova which are developed in the 

 gonophores to ciliated plauulee, which on their escape 

 through the ruptured sac undergo remarkable changes 

 in shape. They have been observed to enter upon 

 their fixed state in a few hours. 



This is the only fixed Hydroid living in fresh 

 water. It appears to have originally flourished in 

 brackish water, and has only very recently been 

 known to inhabit fresh water. Prof. Carl Semper* 

 says, " that when he was a student it was only found 

 in estuaries and at the mouths of rivers, where the 

 * " Animal Life," 152. 



