U BRITISH FOSSIL CORALS. 



of unequal size towards the calicular edge. Calice almost circular, or somewhat oval and 

 shallow. Columella fascicular, well developed, not prominent at its apex, and terminated 

 by ten or fifteen papillae of equal size. Septa forming four complete cycla and six well- 

 marked, equally developed systems, in which, however, the secondary ones differ but little 

 from those of the first cyclum. The septa are slightly exsert, closely set, unequal, and 

 rather thicker outwards than towards the columella. Pali narrow and unequal; those 

 corresponding to the tertiary septa broad and rather stout ; the others, and most especially 

 those corresponding to the primary septa, narrow and thinner. Height of the corallum, 

 seven or eight lines ; diameter of the calice, almost seven lines. 



This species belongs to the first section of the genus Trochocyathus (T. siwpliccs), and 

 differs from T. iv/pari-partilus 1 and T. Bellingherianus by not having a fifth cyclum 

 of septa; its general form distinguishes it from T. mitratus? T. crassus, T. simplex, and 

 T. costulatus, which are all short, broad, and curved ; and from T. elongatus, T. Konincldi, 

 and T. gracilis, which are much elongated, curved, and very narrow towards the basis. It 

 appears to resemble most, especially by its general form, T. cupula? which is also conical 

 and straight, but this last-mentioned species differs from it by the thickness and strong 

 granulations of the septa, and by the breadth of the basis. 



Trochocyathus conulus appears to have been very widely spread in the seas where the 

 Gault formations were deposited. The specimens which we most particularly studied were 



1 See our Monograph of TurbinolidEe, loc. cit., p. 307. 



2 Since the publication of our Monograph of the Turbinolidse (in 1848) we have recognised that the 

 fossils from Tortona, which M. Michelotti designates under the name of Turbinolia plicata, do not differ 

 specifically from the specimens existing in the Poppelsdorf Museum under the name of Turbinolia mitrata, 

 Goldfuss. As we already expected, the latter specific name must therefore be substituted for the one 

 employed by M. Michelotti, and M. Michelin. 



3 This new species, designated under the name of Turbinolia cupula, by M. Alex. Rouault, (Bulletin 

 de la Soc. Geol. de France, 2 rae serie, vol. ix, p. 20G, 1848), was found by that geologist at Bos d'Arros, in 

 the department of the Lower Pyrennees, and does not appear to differ from a fossil which exists in the 

 collection of M. Fyst, and was found in the Eocene formation at Lacken, near Brussels. Trochocyathus 

 cupula belongs to the first section of our genus Trachocyathus, and presents the following characters : 



Corallum straight, or almost so, subturbinate, but short, and having a broad peduncle, but not remaining 

 adherent in the adult state. Castas distinct from the basis, straight, unequally developed alternately, 

 rather prominent, especially near the calice, granulated and striated transversely ; rudimentary costse, that 

 do not correspond to any septa, are seen in the intercostal furrows. Calice circular ; fossula not deep. 

 Columella cr ; -ite, well developed. Septa forming three complete cycla, and in general a fourth incom- 

 plete cyclum in one half of three of the systems ; exsert, rather unequal, strong, and presenting on their 

 lateral surfaces large prominent granulations, which are arranged in lines nearly parallel to the upper edge. 

 Pali thick, strongly granulated, and unequal ; those corresponding to the tertiary septa the largest in the 

 half systems where the septa of the fourth cyclum exist, and those corresponding to the secondary septa 

 most developed in the other part of the calice. Height of the corallum, three lines ; diameter of the calice 

 almost as much. By the strong granulations of the septa, and the breadth of its basis, this species tends to 

 establish a transition between the genus Trochocyathus and the genus Paracyathus. 



