124 BRITISH FOSSIL CORALS. 



Microsohna tuhcrosa} M. racemosa,^ M. excelsa^ and M. incrustata,^ difFer from it by the 

 septa being thicker and the general form of the corallmn being subdcndroid. As to 

 Microsolena irregulans^ it appears to be an undeterminable specimen of some Thamnastrea ; 

 nor does the Badylastrea subramosci' of M. D'Orbigny belong to this genus, being identical 

 with our Thamnastrea a finis? 



2. Microsolena excelsa. Tab. XXV, fig. 5. 



SiDERASTR^A INCRUSTATA, M'Coij, Anil, and Mag. of Nat. Hist., s. ii, v. ii, p. 419, 1848. 



(Not Siderastrea incrustata,'M.\c\vGYm, Icon., 1845.) 



Corallmn subdendroid, composed of erect cylindrical digitiform ramified branches. 

 Basis covered with a thick, wrinkled, common epitheca, which forms also a few small zones 

 at various heights up the branches. The rest of the surface covered with calices, the centre 

 of which is occupied by a well-defined but shallow fossula. The corallites are crowded 

 together, almost equally developed, and their calices are somewhat polygonal. The columella 

 appears to be papillose, but rudimentary. In general, there are about twenty-four septa, and 

 consequently three cycla, but sometimes a certain number of the tertiary ones are wanting. 

 The septa are confluent, almost equally developed, rather closely set, thin, and bent or 

 flexuous outwards. They are composed of distinct trahicula, arranged much in the same 

 manner as in the preceding species. 



This fine fossil coral forms probably long tufts, but we have seen but fragments of 

 about three inches long ; the branches are six or seven lines in diameter, and tlie calices 

 about half a line. The specimen here described belongs to Mr. Walton's collection, and 

 was found in the Great Oolite, near Bath. Prof. M'Coy mentions its having been met with 

 in the Great Oolite at Minchinhampton. 



M. excelsa is very much like M. incrustata^ to which Prof. M'Coy referred it ; but in 

 the latter the epitheca is much more abundant and the calices are shallower. M. tuheroscv' 

 is distinguished by its general form being massive and mammose, but not dendroid, and 

 M. ramosc^^ by the septa being much thicker and less numerous. 



The fossil described by Prof. M'Coy under the name of Goniopora uacemosa^" appears 

 to difier very little from Microsolena excelsa ; it was found in the Great Oolite at Min- 

 chinhampton, 



^ Alvcopora tuherosa, Miclieliii, Icon., tub. xxix, fig. 7. 



2 Aheopora racemosa, ibid., tab. xxix, lig. G. 



^ Tab. xxix, fig. 5. 



* Aheopora incrustata, Miclieliu, Icon., tab. xxix, fig. 8. 



5 D'Orbigny, Prodr., tab. i, p. 222. 



^ D'Orbigny, Prodr., tab. ii, p. 97. 



''' Milne Edwards and J. Ilaimc, Ann. Sc. Nat., tab. xii, p. 158. 



^ Michelin, tab. xxix, fig. 8. » lb., tab. .\xi.x, fig. 7. '" lb., tab. xxi.T, fig. 6. 



