174 



Brora, Mr. Robertson has discovered two beds abounding in Cyclas 

 and other freshwater fossils, approachable only at low water. The 

 rise of the tide on the occasion of his visit to the locality, prevented 

 a minute examination of their relations. Their position was however 

 satisfactorily made out, and is, in the descending order, as follows : — 



a. Beds of calcareous sandstone, considered by Mr. Phillips to re- 

 present the gray limestone of Cloughton and other localities in York- 

 shire. 



h. Shale and coal, several feet. 



c. Shale with fossils about an inch. 



d. Shale and coal similar to the beds b, two or three feet. 



e. Clay with fossils about thirteen inches. 

 f. Shale with a few plants. 



The bed c has yielded, — 



Fishes; — Scales of a species of Lepidotiis, strongly resembling L. 

 fimbriatus, Ag. Scale of Megalurus ? 



Mollusca, Paludina, several new species. Cyclas, one or two new 

 species. 



Crustacea. — Cypris, new species. Plant, obscure impressions. 



From the bed e the following have been obtained : — 



Fishes. — Scales of two or three species of Lepidotiis. Teeth of 

 Acrodus minimus, Ag. ? Teeth of Hybodus minimus, Ag. 



Mollusca. — Paludina, same species as in the upper bed. Two or 

 three species of Perna, some of which are probably new. Unio, one 

 new species. Cyclas numerous, new species chiefly belonging to 

 Lamarck's genus Cyrena*. 



Crustacea. — Cypris, same species as in the upper bed. 



Plants. — Minute fragments of carbonized wood. 



Nearly the whole mass of both beds consists of fossils. No ma- 

 rine fossils (with the excej^tion perhaps of the scales of Lepidotus) 

 are found in the upper bed, and it seems therefore to be properly a 

 freshwater deposit. The mixed nature of the fossils of the lower 

 one conclusively point out its estuary character. 



" Observations on the occurrence of Freshwater Beds in the Ooli- 

 tic Deposits of Brora, Sutherlandshire ; and on the British Equiva- 

 lents of the Neocomian System of Foreign Geologists." By Rode- 

 rick Impey Murchison, Esq., F.G.S. 



In this communication the author confirms the interesting disco- 

 very announced by Mr. Robertson in the preceding paper, and re- 

 marks, that as the reefs of rock exposed at low water at the mouth 

 of the river Brora unquestionably lie beneath the Oxford clay, and 

 are not far above the roof of the coal, there can be no doubt that the 

 beds containing the freshwater shells, being fairly intercalated with 

 the other strata, are thus inclosed in the heart of the oolitic series. 



* Among the specimens sent to the Society by Mr. Rohertson were se- 

 veral examples of Cyclas media, identical with the Wealden shell. The 

 Perna referred to is altogether new, and will pvohably form the type of a 

 genus, bearing a relation to Perna analogous with that which Dreissena 

 biears io My tilus. 



