of the Great Oolite of Minchinhampton. 119 



foreign to the deposit : these conditions vary and change every 

 few yards, as Ukewise does the mineral character of the beds ; — 

 the results, in fact, of littoral action ; of a shallow sea where the 

 shells were subjected to strong currents producing hasty de- 

 posits and frequent trituration. The oolitic structure is rather 

 scanty and very uncertain. As a complete contrast to these 

 conditions, the Great Oolite in the vicinity of Bath may be cited. 

 The rock is there thick-bedded ; the oolitic structure prevails ; 

 the shells are few, and those chiefly Terebratula ; the denizens, 

 it may be presumed, of a deep and tranquil sea, in which corals 

 and sponges multiplied and attained large dimensions. In Mr. 

 Lonsdale's list of 31 species of Mollusca from the Bradford clay, 

 Bath oolite and Fuller's earth of that neighbourhood, no less 

 than 8 are Terebratula, and a Crania has since been added; 

 a larger number of Brachiopods than will be found in the 327 

 Minchinhampton species which I have tabulated. 



The list given by Mr. Buckman, in his ' Geology of Chelten- 

 ham,' from the Bradford clay and Stonesfield slate of the Cot- 

 teswolds in the north-eastern part of this county, comprises 

 5 Radiaria, 2 Terebratulse, 44 Bivalves, 6 Cephalopoda, and 19 

 Univalves. Stonesfield has yielded a rich store of remains of 

 reptiles, fishes, Crustacea and land plants, but the conchologi- 

 cal list is but meagre, and we are nearly destitute of information 

 with regard to the shells of the Great Oolite in its long coiu'se 

 through the counties of Northampton and Lincoln. Yorkshire, 

 on the other hand, has found able illustrators in Phillips, Wil- 

 liamson and Bean, the latter gentleman having given, in the 

 ' Magazine of Natural History for 1839,' a list of fossils from 

 the stratum called Cornbrash in that county, consisting of 4 

 Radiaria, 3 Annulata, 91 Bivalves, 16 Univalves, and 3 Cephalo- 

 poda. Unfortunately, however, the rocks beneath the Oxford 

 clay in that county form a great carboniferous series of deposits 

 accumulated in an estuary, and will not allow of its subdivisions 

 being identified with those of the middle and west of England. 

 From this cause the shells have little more than a local value, 

 since we cannot be sure that any particular stratum is contem- 

 poraneous with another in a different locality. On looking at 

 these lists, together with those relating to the oolitic rocks of 

 France, Germany and Switzerland, we are struck with the great 

 paucity of univalves as compared with the small district of Min- 

 chinhampton. 



A careful scrutiny however of various foreign works which 

 bear upon the subject, — of the works of Goldfuss, Roemer, Dun- 

 ker, Dcslongchamps, d'Archiac, &c. — has convinced me, that if 

 any peculiarity exists with regard to the Minchinhampton fos- 

 sils it is at least of a very limited nature, inasmuch as nearly 



