190 E. E. TOMES Otf THE GREAT-OOLITE MADEEPOEAEIA. 



especially those near the base of the corallum, are quite different. 

 They are far apart, small, round, very clearly denned, and rather 

 prominent. The septa are short, thick, and of equal size at their 

 outer and inner ends. The fossula is small and well defined. The 

 septal costae are long, very uniform in size, closely placed together, 

 and have a parallel arrangement. They are not so stout as the septa ; 

 and a distinct notch, which often divides them from the septa, gives 

 to the latter the aspect of a ring of pali. Both the septa and their 

 costal continuations are very delicately and finely papillated ; they 

 might almost be said to be granulated. 



Distance from centre to centre of the calices 1| line, diameter of 

 the calices 1 line. 



The figures given by Prof. Duncan as of this species*, but unac- 

 companied by letterpress, must, in my opinion, be referred to some 

 other species which has the septa more strongly geniculated. 



At present I have only seen specimens of this species from Pair- 

 ford ; but it is very common there. 



Thamnastr^a mammosa, M.-Edw. & Haime^ Brit. Foss. Cor. p. 119. 



From the surface of a ploughed field on the Stonesfield side of the 

 Great Western Railway two examples have been obtained, which 

 have all the calicular characteristics of the species as given by MM. 

 Milne-Edwards and Haime, but differ considerably from their figure 

 in the general form of the corallum. Although they possess the same 

 nodular and gibbous upper surface, they are much more expanded 

 and depressed. 



In a bed immediately overlying the Stonesfield Slate at Aylworth, 

 on the Bourton-on-the-Water Railway, specimens of this coral have 

 been collected by me which more nearly approach the upright form 

 represented in their figure. It appears at that place to be a com- 

 mon species. A few small specimens have also been found at Fair- 

 ford ; but it is probably there, as well as at Stonesfield, rather rare. 



Genus Microsolena, Lamx. 



Microsolena excelsa, M.-Edw. & Haime, Brit. Foss. Cor. p. 124, 

 tab. xxv. fig. 5, 1851. 



It was from specimens in Mr. Walton's collection that the figures 

 and description of this species which appear in the great work on 

 'British Fossil Corals' by MM. Milne-Edwards and Haime were 

 taken ; and I have had the advantage of specimens from the same 

 collection for comparison when identifying the species mentioned in 

 the present communication. By their assistance I have determined 

 with certainty examples from Fairford, Stonesfield, and Bollright, 

 at all which places it is a common species. 



In the early periods of its growth, M. excelsa is very peculiar. It 



then presents the appearance of a cone attached by a broad base, the 



summit of which is obtuse, and has a single large calice, while around 



the sides there is a circle of smaller calices, just as in Oenabacia. 



* Supp. Brit. Foss. Cor. pt. iii. pi. ii. figs. 6-9. 



