306 CYPRINIDiE. 



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 



" 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," 



might have had the same effect on shells of C. Islandica 

 formerly exposed on an Arctic beach, as boiling water has 

 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 Midler's time the animal was eaten by the 

 natives of Iceland, and called by them " Ku-skisel " 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- 



