22 
THE BORING HABITS OF THE PHOLAS. 
W. HARRISON HUTTON. 
REFERRING to the previous notes on this subject by Dr. Irving 
and myself, which have appeared in The Naturalist, from a 
discussion which subsequently took place at a meeting of 
northern conchologists, it was apparent that some still held 
the opinion that these shells bored by the aid of a secreted 
acid. One gentleman even exhibited a small piece of bored 
rock in which was a slight projection, as evidence against the 
theory of the rotatory method of boring. Since then I have 
spent some weeks at Scarborough, and while there I collected 
a number of Pholas and submitted them, and their various 
organs, to a number of chemical tests for acid. I also placed 
blue litmus paper in the holes of the molluscs, in their natural 
habitats, and in no case was there the slightest evidence of 
change, which would have been the case had there been any 
traces of acid present. In none of the tests, either with the 
shells in position, or with their dissected parts, did I find the 
slightest indication of the presence of acids. This seems to 
indicate that the animals do not secrete any acid that would 
assist them in any way in their work of rock-boring. 
I may add that among the many who still hold the opinion 
that acid assists the molluscs in their work I have not found 
anyone who have kept any of the species in confinement and 
studied their habits. 
—_!: 0 .—— 
Catalogue of the Species of Pisidium (Recent and Fossil) in the collection 
of the British Museum (Natural History) with notes on those of Western 
Europe. By B. B. Woodward. London: Longmans, Green and Co., 
etc., 1913, pp. x. ++ 140 and 30 plates. In this Catalogue a departure 
has been made by the Museum Authorities, inasmuch as the specimens 
from two departments are figured and described. Seeing, however, that 
it is sometimes difficult to distinguish between the recent and some of 
the post-glacial beds, and that Pisidia occur in both, the authorities 
have been well advised in bringing their various species together in one 
monograph. Collectors have long neglected this group of shells on account 
of the great difficulty in the way of identification, due to the small size 
and general similarity of the various species. Mr. Woodward, after several 
years’ study of the genus, has been able to unravel the tangle. He describes 
fifteen different species, gives the complete synonymy of each; the 
original description, and a detailed description on a modern basis. There 
is also a vice-county record of the occurrence of the different forms, and 
distribution maps showing the records of recent and fossil species. Un 
fortunately these refer only to such specimens as happen to be in the 
national collections, though it may serve as a hint to possible benefactors 
as to the areas from which specimens are desired. For example, no fossil 
Pisidia are recorded from Yorkshire in any of the maps, whereas, of course, 
the Geological Survey and other Government publications record several. 
There is a bibliography of nearly 200 entries, but a most valuable aid to 
collectors occurs in the 30 plates upon which several hundred specimens 
are beautifully figured. These illustrations, showing the various varieties 
of the different species, should make the question of identification a very 
simple one. 
> 
1913 Juner. R 
