CORALS OF 'THE LONDON CLAY. 33 
systems are apparently double, so that the septal apparatus is divided into eight nearly 
equal groups. Stylocenia Lapeyrousiana differs from it by its conical form, and by the 
existence of three complete cycla of septa. Stylocwnia Taurinensis has equally but two 
septal cycla, but the mural processes are much smaller than in 8. monticularia ; the calices 
are larger, and the primary septa are united to columella very high up. 
Stylocenia monticularia has been found at Bracklesham Bay, by Mr. Frederick Edwards, 
but appears to be rare in that locality ; it is, on the contrary, very common at Grignon, 
and in many other places near Paris. 
2. Genus ASTROCENIA (p. XXx). 
ASTROC@NIA PULCHELLA. Tab. V, figs. 3, 3a, 346, 3c. 
Corallum composite, astreiform, massive, or subcolumnar, and presenting at its under 
surface a common plate, covered with a complete epitheca, delicately wrinkled by concentric 
striae. Corallites approximating more or less, according to the age of the Coral and the 
degree of. activity with which gemmation has been carried on. When the corallites are 
not crowded together, the calices are circular, and have a distinct though not prominent 
edge; they are also separated by a pseudo-ccenenchyma, the surface of which is covered 
with small costal ridges, that are usually denticulated, so as to assume the appearance of 
rows of round, obtuse granule (fig. 3c). When the calices approximate, they become 
somewhat polygonal, and their margins are separated only by a narrow furrow, or united 
so as to appear simple. The calicular fossula is very shallow. Colwmella cylindrical, 
obtuse, and free to a considerable extent, but not rising quite so high as the septa. Three 
complete cycla of septa, and six equally-developed systems; the septa of unequal size, 
according to their relative age, straight, slightly exsert, closely set, feebly granulated, rather 
thick externally, and having their upper edge entire and convex. Breadth of the calices, 
two thirds or three quarters of a line. 
This species belongs to the division of the irregular Astroccenia,' for independently of 
the slight mequality perceptible in the size of the calices, it is evident that gemmation takes 
place in this Coral simultaneously at various parts; but it differs from the other species of 
the same section, by the number of the septa; here, as we have already said, the six systems 
are equally developed, whereas in Astrocenia Koninchii, A. Orbignyana, A. reticulata, 
A, ornata, A. ramosa, and A. decaphylia, there is always apparently eight or even ten 
systems. 
We know of only three small specimens of this species, which were found at Bracklesham 
Bay, and belong to the cabinet of Mr. Frederick Edwards. 
me 
1 See our Monograph of the Astreidee, Aun. des Se. Nat., 3° série, vol. x. 
5 
