164 Rev. T. Hincks’s Contributions towards a 
dried ; segments short, stout, the extremities somewhat ob- 
liquely truncate. Zowcia quincuncial, on one surface only, 
rounded above, widest in the middle, contracted below, sub- 
truncate at the base; margins rather prominent, smooth, des- 
titute of spines ; avicularza scattered amongst the zocecia and 
on the same plane with them; area smaller than that of the 
cell, not expanded in the middle, running off to a point below, 
the inferior portion closed in by membrane, the upper occupied 
by the mandible, which is elongate (more than half the length 
of the area), rounded at the apex, and of a dark-brown colour. 
Oecium large (about half the length of the cell), prominent, 
rounded above, inclosed by the membranous front wall of the 
cell above it, the oral margin forming a shallow arch, and 
terminating on each side in a triangular callosity. 
Height of specimen about 1 inch. 
Loc. Off Port Phillip Heads, Victoria (dr. J. B. Wilson). 
The zoarium in this species has a characteristic aspect, due 
to the very short and broad and truncate terminal segments. 
The surface appears rather coarsely reticulate, owing to the 
elevation and distinctness of the cell-margins. The ocecium 
is a marked feature; though overspread by the membranous 
wall, it is less deeply immersed than is usual, and the oral 
arch, with its callosities, stands out prominently. 
EUTHYRIS, nov. gen. 
Der. ed, well *, and @upis (dim. of @vpa), a small door. 
Gen. char.—Zoarium corneous, erect,and foliaceous. Zowcia 
with raised margins; aperture closed in by a membranaceous 
(or membrano-calcareous) wall; orifice surrounded by a chiti- 
nous border ; oral valve furnished with a distinct hinge. 
In this form the simple semicircular opening in the front 
wall of the cell, with the membranous lid characteristic of 
the normal Plustra (and Membranipora), is replaced by a 
much more highly organized orifice, which is bounded and, as 
it were, isolated by a distinct border, and furnished with a 
solid operculum working upon a hinge. We must, I think, 
recognize here the characters of a generic group, in which 
Carbasea episcopalis, Busk, and C. bombycina, Hllis and So- 
lander, will rank, as well as the species which I am about to 
describe. 
MacGillivray has recently constituted a genus under the 
name Thatropora for a parallel group amongst the WMembrani- 
pore t. 
* To suggest the idea of higher structure. 
+ “Descriptions of new or little-known Polyzoa,” Trans. Roy. Soe. 
