CORALS FROM THE INFERIOR OOLITE. 135 
Genus 'THECOSMILIA, (p. XV1.) 
THECOSMILIA GREGARIA. Tab. XXVIII, figs. 1, la. 
MOoNTLIVALTIA GREGARIA, M‘Coy, Ann. and Mag. of Nat. Hist., s. 2, vol. ii, p. 419, 1848. 
Corallum composite, not very tall, lobate, and formed of a thick common trunk, from 
which ascend (diverging in different directions) a certain number of large fasciculi of 
corallites, enveloped in a common strong epitheca. The cadices, when free all round, are 
circular; but those belonging to the same group are in general closely united along the 
line of contact, and then become more or less polygonal : their diameter varies much in the 
different corallites belonging to the same compound corallum, as well as in different 
specimens. In some we have been able to distinguish four complete cycla of sepfa and 
regularly-developed systems; but in most cases, as is usual with fissiparous Corals, it is 
difficult to recognise the divers orders to which these radiate lamin are referable. The 
septa are very exsert, not closely set, thicker externally than towards the centre of the 
calice, in general straight, and terminated by a regularly denticulated edge. The dissepz- 
ments ave numerous. ‘The large specimen figured in this Monograph is about four inches 
high and six inches broad; the calices are in general about one inch in diameter; but we 
have seen some that were one and a half inch in diameter. 
This species has been found at Dundry, Leckhampton, and Crickley, near Chel- 
tenham; specimens are in the collections of Mr. Walton, Dr. Wright, Mr. Pratt, and 
the Museums of Cambridge and Paris. 
Thecosmilia gregaria is remarkable for the manner in which the corallites, arising from 
a common parent, remain for a long time united together after they have become com- 
pletely constituted as individuals. This character is alone sufficient to distinguish it from 
T. trichotoma,’ T. annularis, T. lobata, and T. ramosa* T. Konincki’ differs from it by 
having an additional cyclum of septa; and in Z. Zerquemi*® the septa are thicker, and the 
corallites become circumscribed much more tardily. As to the other species, which appear 
to be referable to the same genus,’ they have not been characterised with sufficient minute- 
ness to enable us to point out the structural peculiarities which may distinguish them 
1 Lithodendron trichotomum, Goldfuss, Petref. Germ., vol. i, tab. xili, fig. 6. 
2yPabyxitl ellen. 
8 Lobophyllia lobata, Michelin, Icon., tab. Ixvii, fig. 3. 
4 D’Orbigny, Prod. de Paldéont., tab, i, p. 292. 
5 Milne Edwards and J. Haime, Ann. des Sc. Nat., s. 3, vol. 10, p. 272. 
® Lobophyllia Terquemi, Michelin, Icon., tab. iv, fig. 6. 
7 See the list of species given in the first part of our ‘Memoire sur les Polyp. des Terr. Palzoz.,’ &e. 
