that afford the Stone sfield- slate. 



417 



rently of mica. The hue is yellowish gray, and the rifts arc coated with 

 yellowish carbonate of lime, crystallized in acute rhomboids. 



5. and 6. The " Cap,'" and " Lower-head'' together, are from eighteen 

 inches to two feet in thickness ; the upper portion having a concretional 

 form like that of the " Pot-lids.'''' And the rock in both cases varies, from 

 a very compact and fine grained grit, effervescing strongly with acids, and 

 having in some places an almost sparry structure, to a stone of which 

 the larger portion consists of oolitic particles. Nearly all the fossils 

 that I have seen are contained in grit more or less oolitic, resembling 

 that above described ; and the greater number, including your speci- 

 men, appear to have been procured from these beds.t 



7. The '^'' Bottom-stuff,'''' about twelve inches thick, is a coarser va- 

 riety of stone, consisting of grit, with a large proportion of oolitic 

 particles, and an admixture of effervescent sand-rock. 



8. I saw no specimens of the floor of the gallery, but it was described 

 by the workmen as of the same nature with No. 7. The workmen also 

 stated that bones are sometimes found in the Rag above the galleries. 

 No. 1, in No. 2, and No. 4 : and they seem to occur occasionally in all 

 the beds enumerated. 



+ The shells, in the specimen represented M Plate XI, are Trigonia impressa, 

 Terebratula ohsoleta, Avicula ovuta, and appmently two species of Grypheea: 

 — and these seem to be among the most abunAnt in the Stoiiesfield slate. Mr. 

 Sowerby's collection and my own contain me following species (including 

 those last mentioned) : many of which, it will oe observed, are knpwn to occur 

 in other places, in the Cornbrash, or upper pa#*of ,t|ke great oolitic group. 



UNIVALVES. 



Nerita, two species ; one banded ; 



another banded and ribbed; 



both preserving their colour. 

 Turritella ? 

 Another spiral univalve. 



BIVALVES. 



Astarte. 



Avicula ovata. Min. Conch. 



Tab. .5 12. f. 2. 

 Gryphaea-two species ; one 



of small size, another 



large T.2l4.f.l. 



Lima rudis T. 214. f. 1. 



Modiola imbricata T. 212. f. 1. 



. aliformis T. 259. 



, a new species . . not figured. 



(bivalves.) 

 Mytilus, a new species . . not figured. 

 Ostrea — a plicated species. 



probably another species. 



Pec ten fibrosus T. 136. f. 2. 



obscurus T. 205. f. 1. 



, a new species. . . . not figured. 



Pholadomya acuticostata. T. 546. 

 Pinna (from Mr. Parkinson's 



collection) not figui'ed 



Plagiostoma, — nearest to 



cardiformis T. 413. f. 3. 



Terebratula obsoleta T. 83. f. 7. 



maxillata . . . T. 438. f. 4. 



Trigonia impressa 



(Sowerby) See PI. XI. 



— Prevost, Ann. des Sc. Nat. 

 IV. PI. 18. f. 22. 23. 



Several of the bones, remains of vegetables, and other fossils which occur at 

 Stonesfield, have been enumerated in Dr. Buckland's memoir on the Megalo- 

 saurus: — Geol. Trans. 2d Ser. I. page 390, &c., — and in Mr. Prevost's paper 

 already referred to. 



Vol. III. 2 d 



