369 



MURICIDiE. 



This important group includes three Grasteropods which 

 have spiral shells, often turreted, and always furnished 

 with a siphonal canal. Many of the largest of testacea are 

 included in it, and some of the most beautiful shells in the 

 world, whether on account of their exquisite colouring or 

 the singularity and eccentricity of their forms. These 

 Mollusks are all predacious and among the most ferocious 

 of their class. They have all a lunate head, cleft below 

 for the mouth, whence protrudes a long proboscis, armed 

 with a denticulated tongue, the teeth on which are arranged 

 in triple rows of three in a row : the central tooth is always 

 augulated and often armed with denticles, the laterals are 

 usually more or less hamate. They have all two branchial 

 plumes, and are in most instances provided with a corneous 

 operculum, the form of which, when taken in relation to 

 the dentition and the characters of the shell, affords the 

 most important bases for generic distinctions. The Muri- 

 cidie, though ranging far back in time, are probably much 

 more extensively developed now than anciently ; the great 

 majority of members of this family are tropical. 



MUREX. LiNN^us. 



Shell strong, variously shaped, always with a tumid 

 body-whorl, which, with the other volutions is crossed by 



VOL. III. 3 B 



