6 BRITISH FOSSIL CORALS. 



Height of coralluin, 7 inches. Breadth, 44 inches. Diemeter of calices, ^ths to ^,ths 

 inch. 



Localiiy. Street, Somersetshire. In the Collection of Dr. Wright, F.G.S. 



The genns Septastrtsa resembles Isastrcen ; but there is fissiparous growth in the 

 calices of the first, and never in the calices of the last-named genus. The peculiar caiicinal 

 gemmation of IsastrcBci never produces septa which, crossing the calice, divide it ofi" 

 into separate individuals. The walls of Sepfastreea are not so perfectly united as in 

 Isasireea. The genus is found in the Lias and in the Tertiary Coral-fauna. 



The shape of the corallum and the septal structures and arrangement distinguish the 

 species from Septastrcea excavata} E. de From., and Septastrcea Fromenteli, Terquem et 

 Piette. 



III. Corals from the Zone of Ammonites angulatus. 



The Sutton Stone" and the deposits at Brocastle, Ewenny, and Cowbridge,' are highly 

 coralliferous beds in Glamorganshire. They rest on the Mountain-limestone, and are 

 covered by members of the Lias higher in the series than the Zone oi Ammonites an(julatus. 

 They have the homotaxis* of the Continental strata, which are classified within the Zones 

 of Ammonites angulatus and Ammonites moreanus, such as the Calcaire de Valogne, the 

 Foie de Veau, in the Cote d'Or, and the Gres Calcareux, in the Duchy of Luxembourg. 

 Their British equivalent strata are well shown at Marton, near Gainsborough, and in 

 Ireland^ near Belfast, besides in the localities mentioned by Dr. Wright.^ 



' Dr. Wright named this Coral Isastraa Haimei, and noticed its specific distinction from Isastrcea 

 Murchisoni, Wright. Its genus is evidently Septastraa, and although Dr. Wright has not published a 

 specific diagnosis of the form, still it is just that it should retain his name. He is answerable for its 

 discovery in the locality given above. 



^ Sir Henry de la Beche, 'Mem. Geol. Survey,' vol. i, p. 270; Mr. Tawney, and P. Martin Duncan, 

 'Quart. Jourii. Geol. Soc.,' vol. xxii, p. 69. 



3 Mr. Charles Moore discovered the Brocastle and Ewenny deposits some years before Mr. Tawney 

 drew attention to the Sutton Stone. He collected a vast number of fossils from them, and forwarded them 

 to me for examination. His able essay on "Abnormal Conditions of Secondary Deposits," &c., was read 

 before the Geological Society, March 20tli, 1867. See my notice of Mr. Chas. Moore's labours, ' Quart. 

 Journ. Geol. Soc.,' Feb. 1867, p- 13. See also "On the Lower Lias or Lias-Conglomerate of a Part of 

 Glamorganshire," by H. W. Bristow, F.E.S. ; ''On the Zone of Ammonites angulatus in Britain," 

 by R. Tate, F.G.S. 



* " On the Madreporaria of the Infra-Lias of South Wales," by P. Martin Duncan, ' Quart. Journ. 

 Geol. Soc.,' 1866, Feb., p. 12. See also Terquem et Piette, 'Mem. de la Soc. Geol. de la France,' 2de 

 s^rie, tome 8, 1865. 



5 R. Tate, ' Quart. Journ. Geol. Soc.,' vol. xx. No. 78, p. 103. 



^ Wright, 'Monogr. Ool. Aster., Pal. Soc.,' p. 13; see also Oppel's ' Juraformation.' 



