CRENELLA. 135 



muscle which connects the terminal lobe with the basal 

 attachment of the foot to the body. While the animal 

 is crawling a tremulous movement is seen to pervade 

 the lobe. The stalk and sheath are faintly wrinkled 

 across. The foot is protruded from the ventral opening 

 in the mantle, and extends in a direction opposite to 

 that of the beaks. 



Col. Montagu described and established this species 

 from a single valve, which was found by his friend 

 Capt. Laskey at Dunbar; but he erroneously supposed 

 it might be the Mytilus faba of Muller. It is the 

 Modiola cicercula of Moller, but not the M. glandula of 

 Totten, which latter species (as Sars has remarked) is 

 more rhomboidal and broader, besides being three or 

 four times the size of our shell. C. glandula and C. 

 faba are more nearly allied. The Mytilus decussatus of 

 Lamarck is a large South American mussel. 



Two specimens of C. faba were procured some years 

 ago by Professor King from the stomach of a wild duck 

 that was shot near Newcastle ; and one of them is in 

 my collection. This shell is common in the arctic zone 

 on both sides of the Atlantic. The bird may have picked 

 up the shells in upper Norway or Iceland ; and better 

 evidence is wanting before C. faba can be admitted into 

 the British fauna. 



Another species, however, of a much more novel and 

 interesting kind has been taken on our northern coasts 

 under similar circumstances. During the severe winter 

 of 1855 several birds of passage were killed near Scar- 

 borough. One of them came into the possession of 

 Mr. Alfred Roberts, an intelligent bird-stuffer, who 

 found a number of small shells in its crop. These he 

 gave to Mr. Bean, and they proved to be the young of 

 Mytilus edulis and Littorina litorea, and an unknown 



