562 R. P. TOMES OJST madreporaria erom the CORAL RAG 



genus Oroseris that gemmation takes place in the outer prolonga- 

 tions of the septal costae. This is exactly what also takes place in 

 the genus Latimceandrarcea, to which genus such species as Oroseris 

 concentrica are very closely affined, if, indeed, they should not be 

 placed in it. 



Latim^akdrar^a corallltsta, E. de Prom. ' Introd. Etud. Polyp. 



Foss.' p. 247. 



A single specimen was found by my friend Mr. T. J. Slatter, 

 F.G.S., amongst the debris of the large quarry between Shrivenham 

 and Highworth *. It differs from specimens received from M. de 

 Fromentel in being more massive in its form, in having the septa 

 and septal costae thinner, their perforations larger, and the synap- 

 ticulae more developed. 



Its greatest diameter is three inches six lines, and it has a height 

 of one inch six lines. 



Latim^andrarjea decorata, Bean, sp. Plate XXII. figs. 7-10 & 15. 

 Meandrina decorata, Bean, MS. 



The corallum is fungiform, and has a thin lobular and somewhat 

 overhanging margin. It is supported on a short peduncle, which 

 has the form of an inverted cone. All the under surface, including 

 the peduncle, has thin, straight, and simple mural costae, which are 

 not very distinct. 



The whole of the upper or calicular surface is formed by the out- 

 ward growth of leaf- like expansions, originating in a central elon- 

 gated leaf, and forming calicular furrows, which are short, broad, 

 and open. There are six of them, besides the central or parent leaf; 

 and they have a somewhat radiate arrangement, and, running quite 

 to the outer margin of the corallum, give to it an undulating out- 

 line. The greatest number of calices in a furrow is two ; but gem- 

 mation is seen to be going on actively around the outer margin of 

 the corallum, in the extreme edge of the leaf-like expansions. 

 There is no evidence of gemmation taking place on the central part 

 of the upper surface. 



The septa are thin, regular, and uniform in thickness throughout, 

 and when unworn have their margins moniliform. A great many 

 anastomose, especially near the outer boundary of the furrows, 

 where they may be regarded as septal costae. 



There are from twenty to twenty-four septa to each calice, and 

 they all pass into the centre of the visceral cavity, and are attached 

 to the columella, which is irregular both as to size and shape, and 

 has a papillated summit. 



The perforations of the septa are not very numerous, and the 



* Since the above was written, I have discovered a young Thecosmilia attached 

 to the specimen above mentioned. This must be taken as additional evidence 

 of its occurrence quite at the base of the Coral Rag proper. 



