GYMNOBLASTEA— ANTHOMEDUSAE 



271 



Fam. Tubulariidae. — This important and cosmopolitan family 

 is represented in tlie British seas by several common species. 

 The zooids of the hydrosojne of Tubularia have two circlets of 

 numerous filiform tentacles. Tlie gonophores are adelocodonic, 

 and are situated on long peduncles attached to the zooid on the 

 upper side of the aboral circlet of tentacles. The larva escapes 

 from the gonophore and acquires two tentacles, with which it 

 beats the water and, assisted by the cilia, keeps itself afloat for 

 some time. In this stage it is known as an "Actinula."^ 



Fam. Ceratellidae. — The colony of Ceratella may be five 

 inches in hei'dit. The stem and main branches are substantial, 



Y\G.\ZZ.—CtiatdUirHsca About 11 it si/c VUlt Baldwin Spencer.-) 



and consist of a network of branching anastomosing tul)es 

 supported by a thick and fenestrated chitinous perisarc. Tlie 



' Tlie aberrant genus Hypohjtus (p. 262) may belong to this family. 

 - Spencer, Trans. Roy. Soc. Vkt. 1892, p. 8. 



