104 MOLLUSC A. 



sufficiently obvious characters of distinction. The V. can- 

 cellata of Linnseus is the type of the genus. 



In the genus TURBINELLUS the shell is turbinated, sub- 

 fusiform, and canaliculated at the base, having from three 

 to five transverse compressed plicae on the pillar. The V. 

 pi/rum is the type of the genus. 



23. BUCCINUM. This is another of the Linnsean genera 

 of shells, which has undergone great alterations. As origi- 

 nally constructed, it embraced many distinct groups of shells, 

 which Bruguiere and Lamark have since formed into ge- 

 nera. The restricted character of the genus Buccinum is 

 thus defined by the last mentioned author : " Testa unival- 

 vis, ovata vel elongata. Apertura oblonga, basi emargina- 

 ta, nudata, canali nullo. Collumella convexa pi ana." 



Bruguiere separated the genus CASSIS, in which the 

 opening is oblong and denticulated on the right side, with 

 a short canal towards the back of the shell. The right 

 margin has a callous border. The Buccinum cornutum of 

 Linnaeus is the type of the species. 



The genus TEREBRA was likewise formed by the same 

 author. It is remarkable for its turreted form, the spire 

 being at least twice as long as the mouth, and the pillar at 

 the base twisted. 



In the genus NASSA the groove in which the mouth ter- 

 minates is reflected as in Cassis, but the left edge of the 

 mouth is callous, and forms upon the pillar a transverse fold. 



The PURPURA is readily distinguished from the Buccinum 

 and Murex, with which it has often been associated by its 

 naked compressed pillar, ending in a point at the- base. 



The genus DOLIUM is distinguished by its bellied forms 

 and transverse rings, together with The margin on the right 

 side being denticulated its whole length. 



