02 
PROCEEDINGS OF THE BRITISH ASSOCIATION. 
animals, during the period of their taking food. He was proceeding to explain 
at some length, when the President observed that as other business pressed, he 
must for the present interrupt the discussion, which he exceedingly regretted, 
both on account of its interest and its importance. 
Dr. Parnell then exhibited some White-bait ( Clupea alba) which he had 
taken in the Frith of Forth, observing that this contradicted the recent news¬ 
paper statement that they existed only in the Thames. 
The Rev. L. Jenyns exhibited a series of specimens of the Square-tailed Shrew 
(Sorex tetragonurus , Herm.), and pointed out the distinguishing characters be¬ 
tween it and the Common Shrew (S.rustieus, Jen.). He also exhibited a 
specimen of the Chesnut Shrew (S. castaneus , Jen.), which he had formerly 
considered as a mere variety of S. tetragonurus , but of which he had now 
seen three individuals, and which he was satisfied deserved to rank as a distinct 
species. It is principally characterized by the bright chesnut colour of the upper 
parts; though there are other differences in the tail and in the form of the 
cranium. It was observed, generally, that the characters of the cranium w r ere 
found of great assistance in determining the several species of this genus. 
Mr. Gray then made some observations on the boring of Pkolades. Pie stated 
that this process had been attributed to two causes—chemical and mechanical. 
Pie was inclined to attribute it to the latter. He exhibited some specimens of 
Chalk which had been bored by^ a Pholas , and pointed out some circular grooves 
which were made in their interior by spines on the outside of the shell, as well as 
a central impression produced by an elongation of the shell to a point, at its 
inferior surface. He stated that the animal did not occupy the whole of the 
cavity it made, but the upper part only.—Mr. Mark, of Newcastle, stated that 
he once had some Pkolades alive in his possession, and had had ocular demon¬ 
stration that they produced the cavities in which they resided, by a circular 
movement of their shells.—Mr. Alder had observed that all the rocks which 
these animals bored were soft under water, and did not become hard till they were 
exposed to the air. He then pointed out the structure of the shells of Pholas, &c., 
that enabled them to bore. Saxicava rugosa had not this structure, and was, 
probably, a chemical borer; Venerupis perforans was supposed to be a borer, 
but he believed it only occupied the deserted tenements of the Pkolades. 
Sir Wm. Jardine then read a report, made at the request of the Association, 
4£ On the Sahnonidce of Scotland.” Pie observed that the fish of Scotland, from 
the alpine or subalpine character of the country, were nearly all Salmonidse. 
Cijprinidce are found to prevail in the south of Britain, but they gradually 
decreased towards the north, and were entirely supplanted by the Sahnonidce in 
Scotland. There is great difficulty in determining the species of Salmo , on 
account of their varying character. The principal points to which inquiry had 
