210 Rev. T. Hincks on the 
Membranipora pallida, n. sp. 
Zoecia elongate-oval, front wall wholly membranous, quin- 
cuncially disposed, margin thin, smooth, usually slightly 
elevated at the top ; an erect spine on each side above and from 
six to eight slender pointed spines down each side, which in- 
cline inward; generally at the bottom of the cell, on a small 
quadrate area, an aviculartum with an expanded base (occu- 
pying the area) and a very long, slender, tapering beak, 
which stretches upward along the margin; mandible trian- 
gular below, above setiform. Occium (?). 
Zoarium whitish, texture delicate. 
Virago Sound; spreading luxuriantly over shell. 
Membranipora exilis, n. sp. 
[ Described in ‘ Annals’ for December 1882, p. 466. ] 
On further examination of this species I find that it agrees 
with MW. radic¢fera, Hincks, in being attached (in some cases 
at least) by radical tubes given off from the dorsal surface. 
It is not closely adnate to the surface on which it grows, as 
most of the Membranipore are, but is furnished with special 
organs of attachment. ‘The first specimen which came under 
my notice (and on which my description was based) is grow- 
ing on Celiaria borealis, the stem of which 7 loosely invests ; 
in this case I have not been able to detect any of the dorsal 
appendages. But on a colony which spreads over a Tubuli- 
pora they are present in great numbers, and there can be no 
doubt that it is anchored by the radical tubes and not adhesive. 
In both cases the dorsal surface of the cells is convex and 
rounded, and clearly unfitted for direct attachment. Probably 
the presence or otherwise of the appendages is dependent on 
the nature of the habitat. 
I have already (‘ Annals’ for July 1881, p. 5, under Mem- 
branipora radicifera) drawn attention to certain links con- 
necting the Membraniporidan series with such forms as 
Bugula and Diachoris. We have another such link in the 
present species. A Membranipora which, from the nature of 
its habitat, had ceased to be adherent and had developed 
radical fibres as a means of attachment, would have made a 
very decided advance towards the Bugulan type. 
Family Porinide. 
Lagenipora spinulosa, n. sp. 
| Described in ‘Annals’ for January 1884, p. 57. | 
When I first described this species I had only met with 
