6 



BRITISH FOSSIL CORALS. 



Height of corallum, 7 inches. Breadth, 4^ inches. Diameter of calices, '^ths to ^ths 

 inch. 



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



The genus Septastrcea resembles Isastrma ; but there is fissiparous growth in the 

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

 gemmation of Isastrma never produces septa which, crossing the calice, divide it off 

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

 Isasircea. 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^Yi. de From., and Septastraa Fromenteli, Terquera 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 of Ammonites angulatus. 

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

 of Ammonites angvlatus 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 ]\Iarton, near Gainsborough, and in 

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



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

 Murchisoni, Wright. Its genus is evidently Septastrcea, 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. 



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

 'Quart. Jouri). Geol. Soc.,' vol. xxii, p. 69. 



3 Mr. Charles Moore discovered the Brocastle and Eveenny 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 20th, 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. 



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



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



