a General History of the Marine Polyzoa. 131 
prolonged below, and become distinctly pyriform. Their 
arrangement is very regularly quincuncial. 
The avicularia are remarkably depressed and scarcely rise 
above the surface. 
Membranipora circumclathrata, n. sp. 
(Pl. V. fig. 1.) 
Zoecia ovate, running to a point below, quincuncially 
arranged, distant, the interspaces areolated; aperture slender- 
oval, occupying about three fourths of the front, and closed 
in entirely by a membranous wall; margin slightly thick- 
ened, crenate, bearing a line of small holes; immediately 
below the aperture a pointed avicularium, elevated on a very 
prominent rising or boss, sloping upwards, the mandible 
directed straight outwards or turned obliquely. Occium 
rounded, smooth, a raised rib across the front a little above 
the opening ; surmounted by an avicularium, which is some- 
times of very large size, with an elongate acute mandible 
pointing obliquely upwards, sometimes of the usual form. 
Loc. Santa Cruz, California, on shell (Miss Jelly). 
The striking characteristics of this attractive species are the 
areolated space which surrounds the cells * and the very 
prominent avicularia. Whether the marginal holes indicate 
the position of as many spines in the perfect state I am unable 
to say ; there is no trace of these appendages in the specimen 
which I have examined. 
Membranipora variegata, n. sp. 
(PI. V. fig. 2.) 
Zocecia ovate, often running to a blunt point below, placed 
closely together, quincuncial, with a thick, rounded, and 
minutely granulated border; aperture occupying the whole 
of the front, slightly contracted above and expanded below, 
with a membranous covering ; four tall spines at the top, a 
little below them a very stout subclavate spine on each side, 
and below these again about six very slender sharply-pointed 
spines, which bend inwards over the area and converge towards 
the centre; all these appendages with a dark-coloured base. 
Avicularia none. Occium (?). 
Loc. Santa Cruz, on shell (Miss Jelly). 
An examination of the marginal zocecia in a colony shows 
that the cell-wall is pierced by a number of large oblong fora- 
mina, placed side by side and separated by a very narrow band 
* In the M. ewrcumceincta of Heller the zocecia are separated by a reti- 
culate or areolated interspace. 
