78 BRITISIL FOSSIL CORALS. 
the other above-mentioned differences do not appear to have sufficient value, and the 
genera Lobocenia, Conocenia, Adelocenia, Tremocenia, Cryptocenia, Dendrocenia, Aplo- 
sastrea, Octocenia, Decacenia, and Pseudocenia of M. @Orbigny, may still remain united 
in a single generical group, under the old name of Sfy/ina. This genus belongs exclusively 
to the secondary period, and most of its representatives are found in strata of the Jurassic 
formation. 
Stylina tubulifera, having 10 principal septa, belongs to the genus Decacenia in M. 
D’Orbigny’s method of classification ; and this peculiarity, which is met with but in a few 
other species of Sfy/zva, distinguishes it from all those in which the calice is divided into 
6, 8, or 12 equal parts. All the S#y/ina which have this number of principal septa are 
very nearly allied to each other, and most of those which are at present considered as being 
specifically distinct, may very hkely prove to be nothing more than varieties of one species ; 
but we have not been able to examine a sufficient number of well-preserved specimens in 
order to decide this question. ‘Thus, S¢y/ina lobata’ may perhaps be a young specimen of 
S. fubulifera, with short corallites, and very prominent, widely-set calices; and Sfy/ina 
octonis* only differs from the above-described species by the calices being more closely set, 
somewhat unequal im size, and about 14 lines in diameter. The specimens on which these 
two species were established are both in a very bad state of preservation. S. tubulifera also 
resembles very much another fossil which was found in the Great Oolite near Bath, and 
will be described in a subsequent chapter of this Monograph, under the name of 8. Ploti ; 
the latter, however, has a smaller co/wmel/a, thinner septa, and less prominent calices. The 
fossil coral mentioned by M. D’Orbigny, under the name of Decacenia magnifica’ is more 
easily distinguished from S. ¢udulifera, and in some calices shows only 8 large septa instead 
of 10, as is the case in most. It is a slightly convex mass, with calices of unequal size, 
but slightly prominent, and of 25 lines diameter; the coste are nearly equal, and delicate ; 
three very small but well-characterised septa exist between each of the principal septa. 
‘This new species appears to have been found in the Coral Rag of Chatel Censoir and of 
Wagnon, Ardennes. We must also add that, by its general aspect, S. fwbulifera resembles 
very much S. /wbulosa,* described by Goldfuss; and in the figure given by that able 
Palontologist, this latter species is represented as having 10 principal septa; but that 
is not in reality the case, for in the original specimen belonging to the Poppelsdorf 
Museum, at Bonn, we ascertained the existence of 12 of these septa. 
1 Explanaria lobata, Goldfuss, Petref. Germ., tab. 38, fig. 5. 
? Pseudocenia octonis, D’Orbigny, Prodrome, vol. ii, p. 34. 
* Prod. de Paleontol., vol. ii, p. 33. 
* Astrea tubulosa, Goldfuss, Petref. Germ., vol. i, tab. xxxviii, fig. 15. 
