242 R. M. Brydone—New Chalk Polyzoa. 
and sharply marked in the upper part but widens towards the lower 
end and almost dies away; on this rim are four pairs of tubercles, of 
which the two highest are prominent and perforated, the third is 
distinctly less prominent and probably perforated, and the lowest 
very faint and probably not perforated; just above the upper corners 
of the area there are sometimes indications of a pair of tiny pores or 
perforated tubercles; the external front wall bears a small central 
perforated boss, which may be shifted to one side when the front wall 
has to accommodate an ocecium, but generally seems to disappear. 
Oecva globular, sturdy, with a concave free edge lying well back 
from the area. 
Avicularia, apart from the possibilities of the central boss, do not 
oceur. 
This species is fairly well distributed, though sparingly, in the 
zone (restricted) of A. quadratus. It has obviously many points 
of general affinity to Jf. missilis, but no close relationship can be 
alleged in view of the following species. 
Memsranrpora cuponata, sp. nov. (Pl. X, Figs. 5, 6.) 
Zoarium unilaminate, adherent. 
Zoecia pyriporiform, small, length about -4 to ‘45 mm.; areas 
slightly elliptical, but almost, sometimes quite, round with an average 
diameter of :16mm.; round their upper end there are about five 
small perforated tubercles; after the early stages a perforated boss 
appears on the front wall and rapidly assumes very large proportions ; 
when the front wall has to accommodate an ocecium, the boss splits 
into what appear under a 3 in. objective to be two tubes generally 
inclined forward and obliquely truncated in the horizontal plane so as 
to give an elongated section, but under a 1 in. objective prove to be 
tiny avicularia of the same general type as those of JL. mussilss, highly. 
exsert, and directed indiscriminately backwards or forwards. 
Oecia very striking, narrow, and very long, and ending in a short 
spike like a dome and cupola; the spike generally projects over the 
area of the succeeding zocecium and so is very plainly visible. 
No vicarious avicularia observed. 
This species, which is very compact and thick in appearance, is 
fairly abundant at ‘'rimingham and occurs also in the Weybourne 
Chalk. Its surface is so uneven that photographs hardly do it 
justice. Its affinity with Jf mussilis is obviously very close apart 
from the avicularia. 
MeMBRANIPORA VECTENSIS, sp. noy. (Pl. X, Figs. 7, 8.) 
Zoarium ‘bilaminate’, branching, branches generally broad; the 
central lamina is very thick in proportion to the zocecia, and occupies 
about three-fifths of the total thickness of the zoarium. 
Zoecia lengthily hexagonal, average length ‘55 to ‘6mm., side 
walls decidedly wide; areas shallow, long and narrow, with a strong 
tendency to pointed ends especially at the lower ends, and often 
sealed by a calcareous lid; they generally stop short some way from 
the lower end of the zoccia, which then have a piriform appearance. 
No oecia or avicularia have been observed. 
