TEREBRA. 93 



Cowry, which, being reflected into an ample fold, is able to 

 envelope the whole shell ; while the locomotive and calcifying 

 organs are extremely limited in their dimensions, owing to 

 the confined nature of his habitation, although the latter 

 is exercised with a degree of surprising energy. 



Twenty-four genera belong to the family Furpurifera ; 

 among which the Terehra and Oliva, the Ehurna, Bulla, 

 Buccinum, and Magilus, the Purpura, Bolium, Harpa, and 

 Cassis, are deserving of particular attention. 



The animal inhabitant of Terehra has a small head and 

 tentacles, and the entire mass rarely extends beyond a tenth 

 of the shell. But, although encumbered with a shell ten 

 times the length of his body, the creature is far more 

 active than his relative the Mitre ; his shell, though longer, 

 is not of such overbalancing proportions, and the weight 

 being chiefly at the base, enables the mollusk to move some- 

 what readily, by the force with which he secures his muscular 

 disc to some contiguous rock or tuft of sea-weed. 



Terehrm chiefly inhabit the eastern world, and are re- 

 stricted to warm temperatures ; one small species, only, 

 extending as far north as the Mediterranean. 



The enamelled exterior of the Olive-shell indicates that 

 it is more or less enveloped, like the Cowry, with a portion 



