CORALS FROM THE INFERIOR OOLITE. 135 



Genus Thecosmilia, (p. xvi.) 

 Thecosmilia gregaria. Tab. XXVIII, figs. 1, la. 



MoNTLiVALTiA GREGAKIA, M'Coij, 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 diiTerent directions) a certain number of large fasciculi of 

 coralhtes, enveloped in a common strong epitheca. The calices, 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 sejita 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 laminae 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 dissepi- 

 ments are 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. lohata^ and T. ramosa* T. Konincld^ differs from it by 

 having an additional cycluni of septa ; and in T. Terquemi^ 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 



^ Lithodendron trichotomum, Goldfuss, Petref. Germ., vol. i, tab. xiii, fig. 6. 



2 Tab. xiii, fig. I. 



3 Lobophyllia lohata, Micbelin, Icon., tab. Ixvii, fig. 3. 

 * D'Orbigny, Prod, de Pak'ont., tab. i, p. 292. 



^ Milne Edwards and J. Haime, Ann. des Sc. Nat., s. 3, vol. 10, p. 2/2. 



® Lobophyllia Terquemi, Miehelin, Icon., tab. iv, fig. 6. 



^ See the list of species given in the first part of our ' Meraoire sur les Polyp, des Terr. Palseoz.,' &c. 



