NATURAL HISTORY SOCIETY OF GLASGOW. 93 



informed us that it was discovered many years ago by a fisherman 

 when cutting a canal fiu'ther into the bay, for the better accommoda- 

 tion of his boat. Mr M'Niven also told us that about eight years 

 ago he procured a barrel full of the clay containing the shells, and 

 forwarded it to our late Secretary, Mr Fraser, who appears to 

 have altogether overlooked the circumstance. 



There can be little doubt but the shells have been drifted to 

 where they are found, but probably from no great distance. 

 Although marine shells, they are met with in brakish water; the 

 Rissoa ulvae and Tellhia solidula are purely estuary shells. Per- 

 haps the best mussel fishery we have in the West of Scotland is 

 between Greenock and Port-Glasgow, where there is a great 

 admixture of fresh water. Regarding the whelk and the cockle, I 

 am not prepared to say what they could bear; but as all littoral 

 shell fish are often exposed to heavy rains, it is most likely that 

 they could also endure a considerable admixture of fresh water; 

 and there is little doubt, at the time they lived, the tide supplied 

 the salt water. 



II. — An account of a visit to the shores of Dmibar in February last, 

 with Descriptive Notes on the Natural History of the District. Part 

 II. By the Secretary and Mr David Robertson. 



Among the numerous objects exhibited in illustration of the 

 paper, there were several slabs of clay from the Westbarns clay- 

 field, containing very distinct tracks of some molluscous animal, 

 or a crustacean. These tracks were distinguishable only on the 

 thin layers of sand occurring in various parts of the bed, and, 

 after the closest examination, no trace of any other animal could 

 be perceived. Regarding the extreme abundance of the recently 

 discovered fossil star-fish, Ophiolepis gracilis, in this clayfield, it was 

 stated that Mr Robertson had, during a recent dredging excursion, 

 in the Firth of Clyde, brought up two successive hauls of star-fishes 

 — the dredge in each case being literally full of a single species of 

 Oj.)hiura, without a fragment of any other creature, showing the 

 ground on which the dredge was acting to be completely covered 

 by these animals alone. This fact, while suggestive of the 

 gregarious habits of certain species, throws some light on the 

 conditions under which these fossil remains are found in the brick 

 clay; and it would appear their immense numliers contribute in 



