146 Geological Society. 



Icon. Sowerby, Thesaurus Conch., pi. xxix. f. 211, 212. 



Hah, Ad Meridam, Columbiae Occidentalis. From the collection 

 of H. Cuming, Esq. 



This ver)^ peculiarly striated shell was lately found by a gentleman 

 whilst searching for Orchidaceous plants at the base of the Cordil- 

 leras Mountains. 



GEOLOGICAL SOCIETY. 



April 5, 1843. — "Notice of the occurrence of Beds containing 

 Freshwater Fossils in the Oolitic Coal-field of Brora, Sutherland- 

 shire." By Alexander Robertson, Esq., F.G.S. 



Among the reefs of shale and coal opposite the old salt-pans at 

 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 Lepidotus, strongly resembling L. 

 fimhriatus, 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 Lepidotus. 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 excejjtion 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. 



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

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

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

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

 bears to Mytilus. 



