P.. P. TOMES ON THE GEEAT-OOLITE MADREPOPAEIA. 187 



Thecosmilia obtusa, Dime. Supp. Brit. Foss. Cor. pt. iii. p. 14, pi. i. 

 figs. 1-4. 



The coral figured by Prof. Duncan in his Supplement to the 

 British Fossil Corals of MM. Milne-Edwards and Haime, under the 

 name of Thecosmilia obtusa, was received by him from Mr. Brown 

 of Cirencester, and, I have no doubt, was one of the Fairford corals. 

 There are many such in the collection made by Miss Slatter at that 

 place. These I have examined with great care, and am fully 

 satisfied that they are not referable to the genus Thecosmilia. 



In its general form this species is tall and turbinate, and attached 

 by a rather narrow base. With upward growth the calice becomes 

 lobular, and increase takes place by gemmation in the ends of the 

 lobes. A number of corallites is the result, which may either 

 remain attached to each other or become free. They all spring from 

 nearly one level ; and the greatest number I have seen is four. 

 More frequently there are two or three. 



Genus Astroccenia, M.-Edw. and Haime. 



Only one undoubted Oolitic species of the genus is given by MM. 

 Milne-Edwards and Haime in their General History of Corals *. It 

 is the Astroccenia tubercsa of d'Orbigny, and was met with in the In- 

 ferior Oolite of Luc. Four doubtful ones are also given, namely : — the 

 Prionastrcea microcoma of d'Orbigny, from the Middle Oolite of Neu- 

 vizi ; the Astrcea sancti-mihieli of Michelin, from the Middle Oolite of 

 Saint-Mihiel ; the Astrcea crasso-ramosa of the same author, from 

 the same formation and place ; and the Astrcea pentagonalis of 

 Goldfuss, from the Middle Oolite of Wiirttemberg. The last-named 

 species, however, has been doubtfully referred by Becker and Milas- 

 chewitsch to the genus Stephanocceniaf . 



M. de Fromentel has described and figured a well-marked species 

 from the Portlandian beds of Mantoche under the name of Astroccenia 

 triangularis %. In his ' Introduction ' §, only that species is men- 

 tioned as an unquestionable Oolitic Astroccenia, all the others (including 

 Astroccenia tuberosa, which was evidently regarded by Milne-Ed- 

 wards and Haime as a true Astroccenia) being included in the list 

 of doubtful species. Nothing new respecting the genus Astroccenia 

 appeared in the subsequently published work by the same author on 

 the fossil corals of the environs of Gray. 



From this we may conclude that the genus has been, up to the 

 present time, represented by very few, if by more than one, undoubted 

 Oolitic species ; and the interest attending its present introduction 

 into the English list is not lessened by its comparative rarity in 

 the Jurassic formations of other countries of Europe ||. 



* Hist. Nat. Corall. vol. ii. p. 259. t Palaeontographica, vol. xxi. 



\ Bull, de la Soc. Geol. de France, 2me ser . t. xiii. p. 859, 1856. 



§ Introduction a l'Etude des Polyp. Foss. p. 233. 



|| I take the present opportunity of observing that I regard some of the so- 

 called Astroccenia from the South-Wales Lias as clearly referable to another 

 genus. Three Astroccenia from the Lias of France, however, have been described 

 by M. de Fromentel and by MM. Terquem and Piette. 



