MADREPORARIA OF THE BOULONNAIS. 719 
any essential degree from each other. Its habitats are Hourecgq, 
the Mont des Boucards, and Houllefort. 
IsasTRHA PORTLANDICA, E. de From. Monogr. Polyp. Jurass. Sup. 
p. 42, pl. iv. fig. 6. 
A species of /sastrwa having calices which bear some resemblance 
to those of our /sastrea expianata, both in their superficial character 
and in their size, occurs quite high up in the Oolitic formation, in a 
bed which corresponds, as I learn from M. Rigaux, with our Kim- 
meridge Clay. 
In the number of cycles and in the relative length of the septa of 
the different cycles, as well as in the size of the calices, it agrees 
very well with the figure of J. portlandica, to which it must be 
referred. 
Genus Trocnosrrts, M.-Edw. & Haime. 
TROCHOSERIS OoLITICA, n. sp. Pl. XXXII. figs. 10-12. 
Several specimens of a species of Trochoseris, all from the ‘‘ Lower 
grit of Houllefort,” which were forwarded to me several years since 
by M. Rigaux, I believe to be undescribed. I therefore give them 
the above name, and describe them as follows :— 
The corallum has the form of an inverted cone, the diameter of 
which somewhat exceeds its height, and it was attached by its point. 
The mural costz are rather broad, equal in size, rounded and granu- 
lated, and placed closely side by side. They extend the whole length 
of the corallum ; but there are occasional narrow bands of epitheca 
on some of the specimens, especially near to the point of attachment. 
The calice is irregularly round or ovoid, shallow, and the septa, which 
are not exsert, slope into the centre, which is depressed and occupied 
by a small and papillose columella. All the septa are rather stout, 
closely placed, and the shorter ones run into the longer ones, mostly 
forming pairs, though sometimes groups of three or four are formed. 
They are all thicker at their outer than their inner ends, and their 
margins have closely placed tubercles, the longer diameter of which 
‘Is across the septa. here are four cycles and part of a fifth. All 
the septa have their sides ornamented by pointed tubercles (synapti- 
cule) which are rudely arranged in horizontal rows, and when these 
are near the margin of a septum they mix with those on its edge, 
and give to it the appearance of great thickness, The columella is 
small, depressed, and composed of about twenty papille. 
The length of the corallum is from 6 to 8 lines, and the diameter 
from 7 to 9 lines. 
The only species of Trochoseris to which the present bears resem- 
blance is the Trochoseris Morrisi of Duncan*, from the Upper Green- 
sand of Haldon ; but the septa of Trochoseris oolitica are much more 
crowded, anastomose much less, and are less exsert. 
M. de Fromentel 7 has described a Trrochoseris from the Corallian 
* Quart. Journ. Geol. Soc. vol. xxxv. p. 89, pl. viii. figs. 18, 14. 
+ Introd. Etude Polyp. Foss. p. 128. 
