284 Transactions. — Zoology. 



Ilah'itat. — Chiefly in upper harbour, Dunedin, festooned from rock to rock, 

 or between branches of a dead floating tree. A few scattered specimens on 

 Timaru beach. Figs. 12 and 13. 



Sertularia trispinosa, sp. nov. 



Hydrophyton bushy, not creeping, arising in tufts from a spongy-looking 

 hydrorhiza. 



Hydrocaulis very delicate, pale silveiy yellow, dichotomously branched, 

 and subdivided. 



HydrothecaB opposite, distant, tubular, lip oblique, toothed, teeth three, one 

 internal, other two external and lateral, of latter one much larger than the 

 other. 



Gonangia obovate, sessile, smooth, with a small process on each side near 

 the top ; a short neck. 



Habitat — According to variety. 



I hesitated for some time before founding this species, since it resembles 

 in so many respects S. ramulosa and S. bisjnnosa, indeed it is remarkably 

 intermediate between these two species. An ordinary observer seeing one of 

 these varieties on the beach, rolled up in the way it is generally found, would 

 be very apt to mistake it for S. ramulosa, and its colour and delicate nature 

 would further assist in the deception. The opposite cells, the inequality of 

 the lateral teeth, and the difficulty there is in defining the internal tooth, also 

 simulates S. ramulosa. 



In the acuteness of the teeth, in the form of the gonangia, in its general 

 habit, and in the absence of parasitical polyzoa, it resembles a very lax and 

 delicate form of S. hispinosa. I have got large quantities of this variety, and 

 have noted, wherever I found it, absence of polyzoa, and large number of 

 gonangia it bears. This variety is attached to delicate shells, also rarely in 

 single tufts to stems of Boltenias. — Variety a. 



Variety h is never so long and lax as var. a ; more brown in colour ; 

 equally free from polyzoa, and rarely has gonangia, the branchlets generally 

 lean to one side and close somewhat like a Plumularian. Figs. 14 and 15, 

 a and b. 



Sertularia hisinnosa, Hutton. 



Dynamene hisjnnosa, Gray. 



" Hydrophyton long, lax, and strong. Hydrocaulis sparingly dichoto- 

 mously l)ranched, pale brown. 



" Hydrothccaj opposite, tubular; aperture oblicpicly truncated and with two 

 strong teeth on the outside. Gonangia urcoolatc, smooth, with a small tooth 

 on each side at the top. 



