310 BOUGAINVILLIA. 



BOUGAlNFILLIDyE. 



TROPHOSOME.' — Htdkocaulus more or less developed, invested by a con- 

 spicuous PEiiiSAiic. Htdranths witli the hypostome not abruptly differentiated ; 

 tentacles filiform, in a single circlet round the base of the hypostome. 



GONOSOME. — GoNOPiiOKES phanerocodonic, with four simple radiating canals, 

 and with the marginal tentacles simple, and distributed either singly or in clusters. 



The bydranths of all the species included in this family are distinguished from those of the 

 Eudendnda, which they otherwise closely resemble, by the hypostome not being abruptly differ- 

 entiated, as in the latter, but, on the contrary, passing continuously into the body of the 

 hydranth. 



BOUGAINVILLIA, Lesson. 



Name. — In commemoration of the distinguished circumnavigator. Admiral de Bougainville. 



EuDENDRiUM, — Vuii Beneden. 

 Atractylis, — Strethill JVriyht. 

 HippocRENE (planoblast), — Brandt. 

 Margelis (planoblast),— Steens^z-iyj. 



TROPHOSOME.— Hyduophyton consisting of a branching htdrocatous, wdiich 

 is rooted by a filiform nrDuonuizA. Htduanths fusiform, with a conical hypostome. 



GONOSOME.— Planoblasts borne by the hydrocaulus, and having at the time of 

 liberation a deep bell-shaped umbrella, with the manubrium shorter than the height 

 of the bell-cavity, and with four simple labial tentacles, each of which carries at its 

 extremity a little capitulum of thread-cells ; radiating canals, each terminating at its 

 junction with the circular canal in a bulb, from which two tentacles are developed, 

 each tentacle having an ocellus at its base. 



Before attaining maturity, the labial tentacles become dichotoraously branched, and the 

 marginal bulbs carry each a fascicle of munerous tentacles, every one of which has an ocellus at 



its base. 



The genus Bou^ainvdlia was founded by Lesson for a hydroid whose medusa, however, was 



the only part with which he was acquainted. 



