4 Rey. T. Hincks’s Contributions towards 
Membranipora inarmata, n. sp. 
(PI. IV. fig. 4.) 
Zoecia ovate, placed closely together in lines, alternate 
(quincuncially disposed) ; aperture occupying the whole of 
the front, with membranous covering; margins raised, thin, 
smooth, bearing on each side from four to six tall, straight, 
silvery, pointed spines, which are inclined inwards towards the 
centre; at the top asingle erect spine on each side. Avicu- 
laria none. Occtum rounded, very shallow, just covering the 
extremity of the cell, smooth, silvery, often projecting into a 
point in front, with a broad calcareous band stretching over it. 
Loc. Bass’s Straits, on shell. 
In this species the acutely-pointed spines do not bend 
abruptly over the cell, but incline inwards slightly towards 
the centre, the tips almost meeting. The cells are very 
regularly disposed in lines and are placed close together ; 
those in neighbouring rows alternate, so that the arrangement 
is quincuncial. The band across the ocecium is formed by 
the margin of the cell above it. Avicularia seem to be totally 
wanting. There is nothing very distinctive in this form; but 
I cannot identify it with any described species. 
Membranipora vitrea, n. sp. 
(PI. I. fig. 1.) 
Zoecia regularly oval, very shallow; area occupying the 
whole front, and closed in entirely by membrane; margin 
thin, smooth; two rather stout spines on each side at the 
top. Oacium smooth, glassy, broader than high, rather 
flattened, with a raised triangular figure in front, from the 
apex of which a rib passes off to the back. Zoariwm forming 
a delicate network of very fine glassy material. 
Loc. Off Curtis Island. 
The cells are remarkable for their extreme regularity of form. 
Membranipora punctigera, n. sp. 
(PL. IID. fig. 3.) 
Zoecia elongate-ovate, commonly running to a point below ; 
aperture ovate or elliptical, with a membranous covering, occu- 
pying more than three fourths of the front, the remainder 
being filled in by a thin minutely-punctate lamina, which is 
continued up the sides as a narrow edging; margin raised, 
thin, smooth ; at the bottom of most of the cells an avicula- 
rium, slightly raised, with an acute mandible directed upwards. 
