218 



small shell ; " shells and stones, which have been kept 

 quiet in an aquarium for some time, are occasionally 

 covered with it " (T. S. W.). 



Family VI.- Coppiniidae. 

 united by an encrusting, cellular mass. 



Genus COPPINIA, Hassall. 



Der. Named after Mr. Coppin. 



GENERIC CHARACTER. Zoophyte consisting of a number 

 of long tubular hydrothecce crowded closely together and 

 united by an adherent cellular mass, which involves the 

 lower portion of them, the upper portion remaining free ; 

 ova developed in the cavities of the cellular mass, and es- 

 caping as planul<s ; polypites cylindrical and very extensile. 



THIS is an aberrant form amongst the Hydroida; and 

 too little is known of its structure and development to 

 enable us to speak with confidence respecting its relations 

 to its tribe. Its calycle and polypite ally it to the Lafocidce, 

 and it is propagated, like the Hydroida generally, by 

 means of plaiiulae ; but it presents us with several striking 

 peculiarities. The individual polypites are not united at 

 the base by a creeping stem, but are bound together by a 

 spongy, cellular mass, hi which their calycles are plunged, 

 as it were, for a considerable portion of their length. 

 This mass adheres to the surface, and often involves the 

 stem, of various Sertularian zoophytes. 



"Additions to the colony," according to Prof. W. 

 Thomson, ' ' appear to take place by the budding of the 

 hydrse at the base of the tube-like cell, by which process 

 a new hydra is formed, which is separated from its parent, 

 secretes a tube-cell of its own, and ultimately secretes a 



