CORALS FROM THE GAULT. 65 
found near Cambridge, in England ; at Gatis de Gerodot, Dienville, near Brienne (department 
of the Aude), and Etrepy (department of the Marne), in France. Other specimens, which 
in all probability belong also to this species, are designated in M. Michelin’s collection as 
having been found at Novion-en-Porcien ; at Macheromenil, in the Ardennes, and at the 
Perte du Rhone, in the department of the Ain ; but we suspect that some mistake may have 
been made in the labelling of the specimen which is designated in the same collection as 
belonging to the chalk of Tournay, in Belgium. We must also add, that the fossil designated 
by Professor J. Phillips under the name of Zurbinolia conulus was found by that eminent 
geologist at Speeton, in Yorkshire ; but its characters are not sufficiently well known for us 
to be able to identify it with the above-described species, specimens of which exist in the 
collections of the Geological Society, of the Museum at Paris, and of MM. d’Orbigny, 
Michelin, and Milne Edwards. 
M. Al. d’Orbigny has lately given the name of Aplocyathus' to those species of our 
genus Trochocyathus in which the calice is circular. If this new generic division was 
adopted, the species here described would be referred to it ; but that is not, in our opinion, 
advisable. The calice, which is quite circular in a great many species of our genus 
Trochocyathus, becomes slightly elongated in some, quite elliptical in others, and not only 
would the line of separation be difficult to establish between these different forms, but 
certam species which are evidently most closely allied by all their other organic 
characters, would be separated generically in the classification proposed by M. d’Orbigny. 
We cannot, therefore, adopt his views in this respect; but, in justice to that distinguished 
paleontologist, we must remark that the species’ chosen by him as the type of his 
genus Aplocyathus differs much in its general aspect from most species of our genus 
Trochocyathus, and, when more completely known, may be found to present characters of 
sufficient value to authorise the establishment of a separate generic group, which must 
then be so defined as not to comprehend 7. conulus, nor most of the other species that 
have a circular calice. 
2. TrocnocyarnHus Harveyanus. Tab. XI, fig. 4, 4a, 46. 
Trocuocyatuus Harveyanus, Milne Edwards and J. Haime, Monogr. des Turbinolides, in 
Ann. des Se. Nat., 3™° série, vol. ix, p. 314, 1848. 
Corallum simple, straight, short, almost hemispherical, and terminated by a very short 
peduncle, the basal surface of which is concave. Cosfe distinct from the basis, and 
delicately striated transversely ; the primary and secondary ones very prominent and sharp ; 
those of the third cyclum well developed along the upper half of the wall, but those of 
the fourth cyclum very small and obscure. Cadice circular and flat; fossula shallow. 
Columella well developed and papillose. Septa forming four complete cycla; exsert, thin, 
' Note sur des Polypiers Fossiles, p, 5, 1849. 2 The Trochocyathus armatus. 
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