54 GASTEROPODA OF THE INFERIOR OOLITE. 



places, and notably near Doulting and Cranmore, under the very shadow of the 

 Mendips, thick beds of freestone of Inferior Oolite age, as also at Old Ford, near 

 Frome. The well-known section at Vallis, where something like fifteen feet of 

 Inferior Oolite rests on the Carboniferous Limestone, seems to show that only beds 

 of the age of the Glypeus-grit were deposited upon the old ridge at that spot. 

 Why the vicinity of the old reef should have been unfavorable to the accumula- 

 tion of shell-beds with Gasteropoda is very difficult to say. But we find in all 

 cases the border regions to be less rich than the central parts of the several dis- 

 tricts or basins. 



Details op the Cotteswold Disteict. (No. 2.) 



In a sense strictly topographical the country between Frome and Bath can 

 scarcely be regarded as forming part of the Cotteswold Hills, though, to a certain 

 extent, a physical continuation of that range. The exposures of Inferior Oolite 

 throughout this portion of No. 2 District are neither numerous nor important in a 

 palasontological sense. We have already seen that thick beds of pale-coloured 

 oolitic rock (freestones) on both sides of the Mendips replace the rich shell-beds 

 and ironshot Oolites of No. 1 District. This phase continues for some distance 

 north of Frome. The evidences of Gasteropoda are slight, yet not devoid of 

 interest; there is, however, one great drawback, viz. that most of these fossils are 

 in the condition of casts. The high ground north of Radstock is capped by a sort 

 of plateau of Inferior Oolite, and here the following exposures were examined. 



Clan Down. — One and a half miles north-west of Radstock. There are several 

 shallow pits on this down, where the upper beds of the Inferior Oolite have been 

 worked. Of the general development of Inferior Oolite at this spot, and whether 

 there is any representative of the Lower Division, I am ignorant. The unconformity 

 must be considerable, since the Inferior Oolite is represented in the Survey map as 

 resting on Lower Lias ; in one pit, where seven feet of beds are exposed, the upper 

 portion consists of a shivery whitish limestone with a variety of Terebratula globata 

 scattered about, and containing a shell-bed with Trigonia and Nerincea in casts, 

 also Natica Bajocensis and a small Trochus. Below this is a much harder block 

 of stone. Nerincea occurs in casts, rather numerously at the top, and also in a 

 shell-bed lower down. There is more than one species, but Nerincea Guisei is 

 most probably one of them. As we shall see subsequently, this is a very well- 

 marked horizon in the Clypeus-grit, and it is extremely interesting to have obtained 

 proofs of it thus early in our examination of the Cotteswold District. As far as 

 we know at present, this is the most southern locality in England where Nerincea 

 has been found to occur in the Inferior Oolite, and abundantly too, since there are 

 no less than three shell-beds traceable here. 



