Pvn H,i I'UitlS

306 CYPRINID.Ec
heaped up in extraordinary profusion, far exceeding in
number those now thrown up on the adjacent shore.
Neither in the boulder-clay nor in the strata immediately
overlying it are entire valves often to be seen— gene-
rally fragments only, and that part which contains the
hinge, being stronger than the rest of the shell. I
believe this may be explained by an anecdote which I
was lately told by Mr. Bean. Many years ago he found
about a score of fine live specimens on the sands at
Filey after a storm, and triumphantly carried them
home in his pocket-handkerchief. On his return to
Scarborough he put them into a large pan, and poured
boiling water on the heap. To his astonishment and
dismay, a succession of loud reports ensued,
as if a
volley had been fired, and all the shells were either
broken or cracked. The action of severe frost at a
period when the climate and other conditions resembled
those of the Polar region, enclosing
might
"The ice-lock'd secrets of that hoary deep 1
Where fetter' d streams and frozen continents
Lie dark and wild, beat with perpetual storm
Of whirlwind and dire hail,"
have had the same effect on shells of C. Islandica
water has
formerly exposed on an Arctic beach, as boiling
on existing shells of the same species. The fracture may
have been caused by an imperfect cohesion of the material
— the proportion of animal tissue, compared with that of
carbonate of lime, being less in these than in many other
shells. In Muller's time the animal was eaten by the
natives of Iceland, and called by them " Ku-skiael ,} and
" Krok-fishur." In the Shetlands it goes by the uni-
versal name of " clam." This large and unwieldy mol-
lusk contrives to burrow, like a cockle, by
means of its
foot, which is permeated by a series of pores com-
municating with a central tube. This tube opens out-