R. M. Brydone—On Chalk Polyzoa. f 9) 
zocecium there is generally in the central line a buttress distinctly 
bigger than the others, with a considerable interval on either side of 
it. The zocecia are much deeper than those of IL. humiliata, though 
still on the shallow side, and their edges are wrinkled, but so faintly 
that it is only clearly discernible with the larger magnification. 
Oecia more globose than those of IW. humilvata. 
Avicularia very similar to those of IL. humiliata. 
The typical arrangement of the ocecium and avicularium is the same 
as in I, humiliata, but while they never lie side by side, in one instance 
two avicularia have been found to one zocecium, which arrangement 
is at present unknown in JZ. humiliata. 
_ Not uncommon at ‘Trimingham. 
The system of buttressed walls which this species shares with 
MM, humiliata marks them off clearly from all other Cretaceous 
Uembranipore, but the typical arrangement of avicularium above 
ocecium links them, probably only superficially, with IZ. Griffith: pod 
M. Trimminghamensis. 
Memepranrpora TrimmMincHAMENsIs, mihi. PI. III, Figs. 7 and 8. 
I take this opportunity of supplementing from photographs of the 
type-specimen the figure given with the original description. Further 
study has shown that the two upper pairs of granules are perforate 
and the ocecia are shaped like an inverted water-bottle, the expanded 
lip curving round and practically hiding the uppermost pair of 
granules, which are smaller than the succeeding pair. Length of 
area *36 mm., width -28 mm. 
In describing this species (the specific name of which should have 
been spelt Zriminghamensis) and I. Griffithi I omitted to discuss 
Cellepora trifaria, Hag.,' which shows a similar arrangement of 
ocecium and avicularium, relying perhaps overmuch on the facts that 
Marsson did not refind such a form at Rugen, and did not find the 
species recognizable in Hagenow’s collection. The figure appears to 
be taken from a worn specimen, which might equally well be 
M. Grifithi, M. Triminghamensis, or some other species. The de- 
scription only adds the feature of possessing large earshaped avicularia ; 
and these separate it as well from J/. Triminghamensis, which has 
no large avicularia, as from I. Grifithi, which has symmetrical large 
avicularia, while the ear is decidedly unsymmetrical. Cedlepora trifaria 
cannot. therefore be treated as a valid anticipation of either of the 
other species. - 
EXPLANATION OF PLATE III. 
Fic.1. Membranipora huniliata. x 20. 
,, 2. Ditto, another specimen showing perfect ocecium associated with avicularium. 
in typical arrangement. x 20. 
45 Bo LIDAR: Wee 0p 
5, 4. Membranipora anterides. x 20. 
ap Oo JO iinKOST | 5S Zh)s 
,, 6. Ditto, another specimen with the buttresses showing dark against w hite 
chalky >< 20% 
>, 1. Membranipora Lriminghamensis, type-specimen. x 20. 
», 8. Ditto, type-specimen, lighted to show bar across perfect avicularia. x 20. 
1 
Geinitz, Grundriss der Versteinerungshunde, p. 617, pl. xxiiiJ, fig. 40. 
