126 ZOOPHYTOLOGY. 
4. Fam. Mempranirorip®, Busk (‘B. M. C.,’ p. 55). | 
4. Gen. Membranipora, Blainville. 
1. M. tuberculata, Bose. Pl. XVIII, fig. 4. 
Cells oval; margin granular; aperture partially filled in all round by an 
irregular jagged calcareous expansion ; two to four blunt spines or tubercles 
above the cell, often united into a single bifid knob. 
Hab, Madeira, Johnson; Rio de Janeiro, M‘gillivray; Gulf-weed wbique; 
on fuel. * 
Flustra tuberculata, Bose, ‘ Vers.,’ 2d ed., t. iii, p. 143 (ex. syz.) 
Flustra membranacea, Esper, ‘ Flustra,’ pl. v. 
_ This very abundant and extensively spread species we had 
formerly confounded with M. membranacea (‘ B. M. Cat.,’ 
p- 56, pl. lxvin, fig. 2), with which, on superficial inspection, 
we regarded it as identical, until our attention was directed 
to it by Mr. Alder, who was inelined to consider it as dis- 
tinct from that well-known form. We are inclined to regard 
this opinion as correct. The way in which it covers the air- 
vesicles of Fucus natans with its. beautiful calcareous network, 
and spreads over the surface of other Fuci, closely resembling 
the habit of WM. membranacea, taken with the circumstance of 
each cell being crowned with two short tubercular spines, on 
a cursory glance naturally induced the supposition that the 
two forms were identical. They differ, however, in several 
important particulars. MM. tuberculata appears to be far more 
caleareous than M. membranacea, The front of the cell is 
not oblong and angular, as is usually the case in the other 
species. The margin in M. membranacea is thin and smooth, 
and the area is not encroached upon by a calcareous ex- 
pansion. The spines, also, as Mr. Alder points out, in M. 
membranacea are usually, in part at least, flexible or corneous 
(though this is not always the case), whilst in M. tuberculata 
they appear to be invariably calcareous, short, thick, and 
blunt; and in the older cells usually united, so as to form a 
transversely elongated tubercle, thicker and more elevated at 
the sides. The form appears to be confined to the South 
Atlantic, and it is very generally met with on the Gulf-weed. 
With respect to the appellation, it seems quite clear that this 
is the form intended by Bose under the name of Flustra 
tuberculata, and there is no reason, therefore, that his desig- 
nation should not be retained. LEsper’s plate (we have not 
been.able to refer to the text) is a very good representation 
of the species as it occurs on Fucus natans. 
Our figure gives a bad idea of the M. tuberculata, and a 
better will be given in a subsequent number. 
2. M. trichophora, n. sp. Pl. XVIII, fig. 2. 
Front of ecll oval, expanded below and contracted above ; margin smooth 
