ZOOPHYTES. 29 



Sertularia argentea, Ellis and Solander; Hincks, Brit. H. Z. 

 vol. i. p. 268. 



Not common ; from the deep-sea lines of the fishermen. 

 This seems to be a form more characteristic of our southern 

 shores. 



Sertularia cupressina, L. ; Hincks, Brit. H. Z. vol. i. p. 270. 



Very plentiful in the coralline region — sometimes reaching 

 the length of 18 inches. Besides the ordinary form there are 

 two branched varieties. In the first, numerous secondary poly- 

 paries spring from the ordinary dichotomous branches, each 

 twig so burdened being very little thicker than the ordinary 

 forms, and bearing in the usual manner for some distance the. 

 hydrothecse, which gradually become obsolete ; this secondary 

 trunk assumes considerable dimensions, with jointed stem and 

 dichotomous branches, like an independent specimen. In the 

 other variety the main stem itself splits into two divisions, or 

 the secondary trunks throughout are directly connected there- 

 with. 



Sertularia fusca, Johnst. ; Hincks, Brit. H. Z. vol. i. p. 272. 



A single fine specimen only has yet been procured, in the 

 deep water of the bay. Mr. Alder correctly observes that this 

 form leads us to Thuiaria. 



Genus Hydrallmania, Hincks. 

 Hydrallmania falcata, L. ; Hincks, Brit. H. Z. vol. i. p. 273. 



One of the most abundant hydroid zoophytes from the coral- 

 line ground. Its form varies from the elongated spiral to the 

 broadly branched condition ; and it is frequently loaded with 

 parasitic zoophytes, both horny and calcareous. It is a 

 favourite site for Nudibranchiate Mollusca and their ova ; and 

 minute Annelids construct their tubes on every convenient 

 bough. Young specimens are plentiful also under stones 

 between tide-marks, where their habit differs considerably from 

 the foregoing, having the form of a simple straight pinna, 

 generally coated with parasitic structures, both animal and 

 vegetable. 



