78 Proceedings of the Royal Society of Victoria. 



know the exact form or size of the zoarium, as the only 

 specimen I have seen is the small lobe figured, part of Mr. 

 Wooster's single specimen. 



The genus Euthj^-is was proposed by Mr. Hincks (Ann. 

 and Mag. Nat. Hist., August 1882), for a species from 

 Western Australia, which he named E. obtecta. The 

 essential difference between it and Flustra and Carbasea, 

 consists in its having a perfectly formed oral aperture, with 

 the opercular flap attached by a distinct hinge, in the same 

 manner as Thairapora, McG., differs from Membranipora. 

 He referred to the same genus, the Australian Garbasea 

 episcojxdis, Busk, and Flustra bombycina, of Ellis and 

 Solander, from Bahama. The former undoubtedly belongs 

 to the genus, as also probably does the latter, so far as can 

 be determined from the brief description and imperfect figure 

 given. The South African Garbasea. bombycina of Busk 

 fBrit. Mus. Cat. Pol, p. 52, PI. XLVIII, Figs'. 4 to 7), which 

 is certainly not the species of Ellis and Solander, differs 

 essentially in having a true zooecial poi^e, similar to that of 

 Microporella, and has properly in the Challenger Polyzoa 

 (Pt. I, p. 104) been subsequently made by Busk the type of 

 a new genus — Onchoporella. In that work, Busk suggests 

 that his species and Microporella diadema, McG., may be 

 dimorphic conditions of the same species, an opinion for 

 which I cannot see any justification. Independently of the 

 difference of colonial growth, a point of comparatively little 

 consequence, the structure and appearance of the individual 

 zooecia are quite different. In 0. bombycina, they are very 

 slightly calcareous ; there are several perforations on each 

 side in addition to the zooecial pore, and there are no oral 

 spines or aviculaiia. In M. diadema, the zocecia are broader, 

 not so convex, in most forms highly calcified, and the 

 avicularia are constant and very characteristic. 



Membranipora sejuncta, n. sp., PL X, Fig. 5. 



Zocecia oval or elliptical, disjunct, connected by tubes 

 irregular in number and arrangement ; margin thickened, 

 with about six stout spines on each side, incurving ovet the 

 front, and nearly meeting in the central line. Avicularia 

 elliptical, with triangular mandibles, situated above the 

 zooecia in the connecting network of tubes. 



Port Phillip Heads, iVIr. J. Bracebridge Wilson. 



