thai afford the Stoncsjield'slate. 417 



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

 yellowish carboualc 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, eflorvescing 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 Ra§^ 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 in Plate XI, are Trigonia impressa, 

 Terebratula obsoleta, Avicula ovata, and apparently two species of Grypha-a: 

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

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

 those last mentioned) : many of which, it will be observed, are known to occur 

 in other places, in the Cornbrasii, or upper part of the great oolitic group. 



(bivalves.) 

 Mytilus, a new species . . not tigured. 

 Ostrea — a plicated species. 



probably another species. 



UNIVALVES. 



Nerita, two species ; one banded ; 



another banded and ribbed; 



both preserving their colour. 

 Turritella? 

 Another spiral univalve. 



BIVALVES. 



Astartc. 



Avicula ovata. Min. Conch. 



Tab. 512. f. 2. 

 Gryphsea-two species; one 



of small size, another 



large T.214. f.l. 



Limarudis T.214. f.l. 



Modiola imbricata T.212. f. 1. 



aliformis T. 259. 



, a new species . . not tigured. 



Pecten fibrosus T. 136. f. 2. 



obscurus T. 203. f. 1. 



, a new species not tigured. 



Pholadomya acuticostata. T. 546. 

 Piiuia (from Mr. Parkinson's 



collection) not figured 



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 u 



