36 BRITISH FOSSIL CORALS 



Dewalque ; and they remark that the base is ordinarily slightly convex, but sometimes 

 perfectly horizontal ; moreover, they observe that the calice is more convex when the base 

 is horizontal. 



MM. de Fromentel and de Ferry have divided the species Montlivaltia Haimei into 

 three : 



1. Montlwaliia Haimei, Ch. et Dew. 



2. ,, tenuisepta, From, et Ferry. 



3. „ granifjera. From, et Ferry. 



He doubts the propriety of admitting so great a variation in septal number and in 

 septal ornamentation as must be tolerated if the species Avere left entire. 



A very considerable series of specimens of the species has been examined, and the 

 distinctness of such forms as those considered worthy of the specific names tenuisepta and 

 f/ranigera has not been satisfactorily determined. Like the recent simple corals, Montlivaltia 

 Haimei may have had a great variability. It was a very common species, and therefore 

 all the more likely to vary in its shape, septal number, and ornamentation. 



It is evident that there are forms of the species which are either concave or horizontal 

 at the base ; and others which are barely convex at the base, and which may become 

 conical, sensibly taller than usual, and even cylindro-conical in shape. The convexity 

 of the calice, or rather the exsertness of the septa, is often, but not always, correlative to 

 this development of the base, and concave calices are not uncommon in the tallest 

 corallites. The septal number varies in the development of part of the seventh cycle, and 

 the dentate or crenulate condition of the septal edge is very variable. 



The diameter of the calices and the height of the corallum depend upon the age of 

 the individual. 



It would appear that no British specimen exactly resembles the type from 

 Jamoigne, but a variety from the Irish Lias at the Island Magee is nearer to it than any 

 of the British forms. 



Localities. Marton, near Gainsborough ; Newark, Notts ; east shore of Island 

 Magee, North of Ireland. In the Collections of Rev. P. B. Brodie, Mr. Burton, Rev. 

 Mr. ChamberHn, the Geological Society, and the British Museum. 



3. Montlivaltia papillata (sp. nov.). PI. X, figs. 15 — 18. 



The corallum is Cyclolitoid in shape, the base is slightly concave, and the calice is 

 convex, there being a circular depression at the centre. 



The epitheca of the base reaches to the calicular margin ; it is very thin, is 

 marked with concentrical shallow depressions and elevations, and the costse are seen 

 through it faintly. 



The calice is nearly circular. 



