296 INTEODUCTION TO CONCHOLOGY. 



plms, previously known only in the Danube and Yolga, 

 may have been brought to the commercial docks in the 

 Thames, and to Hamburgh, where the species is now 

 domiciled. 



The shells of Crabs and Lobsters are often appropriated 

 to the same purpose by sagacious Mussels and their relatives 

 when about to migrate. A Lobster was taken alive in a 

 drag-net, of wliich the shell was covered with a colony of 

 Mussels ; and within a recent period a large female Crab, 

 loaded with Oysters, and bearing also Anomia epMjjpium 

 and Act'mecEy was captured off the English coast. The 

 Oysters, seven in number, included individuals of six years^ 

 growth, and the two largest were four inches long and 

 three-and-a-half broad. Both the Crab and Oysters were 

 seen ahve by Mr. Eobert Brown ; in reference to wliich Mr. 

 Broderip observes, that " the crab, who was apparently in 

 perfect health, could not have cast her shell for six years ; 

 whereas some naturalists assert that the species moult an- 

 nually, without limiting the moulting period to the early 

 stages of the creature''s growth.''^ 



A right joyous party, doubtless, were those incongruous 

 voyagers, though of different forms and habits ; a silent 

 company assuredly, for none among them could excite con- 



