200 FUNCTIONS AND INSTINCTS. 



Whelks, 1 Tuns, 2 Volutes, 3 Helmets, 4 Rock- 

 shells, 5 Strombs, 6 and other conchs which ex- 

 ceed the general run of shells in beauty, form, 

 and magnitude. But with regard to their habits 

 and instincts we know little or nothing of any 

 interest. 



They are distinguished from the herbivorous 

 ones by breathing the sea-water, for they are 

 all submarine, by means of a siphon or tube, 

 instead of by an aperture in the neck ; in the 

 place of maxilla?, their mouth is furnished 

 with a retractile proboscis, with which they 

 pierce and suck other shell-fish. The aperture 

 of the shell is also very different, the siphon 

 being accompanied sometimes by a channel, 

 and sometimes by a notch at the base of the 

 aperture. 



The tribe most celebrated from ancient times, 

 on account of the vaunted purple die which 

 one species produced, is that constituted by the 

 Rock-shells, or Linne's great genus, Murex, 

 and Lamarck's canaliferous Zoophagans, called 

 so from the long straight canal which terminates 

 the mouth of their shells. The principal fea- 

 ture of this tribe, besides their long channelled 

 beak, is the vast variety of spines, and other 

 processes and ridges, with which their Creator 

 has armed a great number of them ; the 



1 Buccinum. 2 Dolium. ' Valuta. 



4 Cassis. 5 Murex. * Strombus. 



