108 MOLLUSC A. 



with a tooth. The Turbo interstincta, unidentata, plicata, 

 Sandivicensis and insculpta of Montagu, are of this genus. 

 They have no resemblance in their structure to the Lin- 

 naean volutae ; although they have been inconsiderately as- 

 sociated with them by the authors of the Descriptive Cata- 

 logue. The preceding genera are formed of marine shells ; 

 those that follow live on the land. 



In the genus CYCLOSTOMA, the mouth is circular, with 

 united, and often reflected margins. The animal is furnish- 

 ed with an operculum. The T. elegans of Montagu is the 

 only British species of the genus. 



The species which are related to the Turbo bidens per- 

 versus and muscorum of Linnaeus, constitute a very natural 

 family, which may be termed PUPACEA, distinguished by 

 the mouth being furnished with teeth or testaceous lami- 

 nae, and the last whorl nearly the same or less than the pre- 

 ceding. Perhaps the most convenient way of dividing them 

 is into two sections, the first including the dextral, and the 

 second the sinistral shells. 



The dextral pupacea form two genera. The PLTA, as 

 originally constructed by Lamark, was equally faulty with 

 many of the old Linnaean genera. As it has .been restrict- 

 ed to include dextral shells, with the animal possessing four 

 tentacula, with eyes at the tips of the two longest, it can 

 embrace the muscorum, sexdentatus, tridens, and juniperi 

 of Montagu. In the genus CAKYCHIUM, formed by Miil- 

 ler, the tentacula are only two in number, with the eyes 

 placed at the base. It is represented by the T. carychium 

 of Montagu. 



The sinistral pupacea form likewise two genera. The 

 first, which is the Clausilia of Draparnaud, contains sinistral 

 shells, with the animal furnished with four tentacula, with 



