140 BRITISH FOSSIL CORALS. 



at first sight considered them as belonging to two distinct species, but on closer exami- 

 nation that no longer appeared to be the case. 



We are also inclined to think that the Astrca heliantho'ides of Prof. M'Coy' is a worn 

 specimen of the same species, and that the Agaricia elegani of that author may be a 

 young individual of this 27uimnastrea. 



The above-described fossil is found in the Inferior Oolite at Dundry, and in France 

 near Bayeux. Specimens are in the collections of the Geological Society, Mr. Bowerbank, 

 Mr. Walton, and Mr. Pratt. 



Thamnastrea Defranciana is remarkable for its general form, which resembles that of 

 certain sponges, and for the tenuity and close approximation of its septa. It is very nearly 

 allied to a fossil of the cretaceous formations, Thamnastrea conferta^ but in the latter the 

 columella is more developed, and the septa more flexuous. Some other species, T. tenu- 

 issima^ and T. velamentosa^ for example, also bear great resemblance to T. Defranciana, 

 but differ from it by having much smaller calices, thicker septa, and a more developed 

 columella. 



2. Thamnastrea Terquemi. Tab. XXX, figs. 3, 2a, 2*5. 



CoraUum in general thin, circular, and adherent at the centre of its basis, but sometimes 

 appearing to have been quite free ; its common basal plate covered with a thick epitheca, 

 presenting concentric folds or wrinkles ; its upper surface flat or slightly convex. Calices 

 quite superficial and rather closely set. Columella small. Septa from twelve to sixteen in 

 number, unequal alternately, irregularly confluent, often geniculate and grossly granulated 

 laterally. Breadth of the calices two lines. In one specimen the corallum was made up 

 of superposed layers arranged obliquely. 



This species was found by Dr. Wright in the Inferior Oolite near Cheltenham, and 

 by M. Terquem at St. Quentin, near Metz. 



T. Terqiiemi differs from most species of the same genus, by the irregular and rude 

 appearance of the septa ; which are thick, but not as much so as in T. Le/inisi^ and T. 

 Belgical The same character distinguishes it also from T. Mettensis,^ which, in other 

 respects, it resembles very much. 



1 Ann. and Mag. of Nat. Hist., s. 2, vol. ii, p. 401. 



2 Op. cit., p. 418. 



3 Synastrea confertn, Milne Edwards and J. Ilaime, Ann. des Sc. Nat., s. 3, vol. xii. p. 190. 



* Synastrea tenuissima, Milne Edwards and J. Haime, loo. cit., p. 191. 



* Astrea velamentosa, Goldfuss, Petref. Germ., vol. i, tab. x.\iii, fig. 4. 



•• Astrea Lennisii, Roemer, Verst. des Norddeut. Kreid., tab. xvi, fig. xxvi. 

 7 Milne Edwards and J. Haime, Polyp. Foss. des Terr. Palseoz., &c., p. 100. 

 ^ See tab. xxx, fig. 3. 



