356 



trees : and in Devonjldrc near Kingsbridge, under the 

 loofe bark of old apple trees, where no oiher Ihell was 

 to be met with, but T. Mufcorum. 



No (liell feems to have puzzled conchologifls more 

 than this ; being generally placed in cabinets as the 

 young of T. bidens. 



The difficulty of obtaining a fpecimen, with a perfeft 

 full grown mouth, has probably led to this error. It 

 differs however in fhape, fize, and colour, particular- 

 ly in the bottom volution, which is even and round ; 

 whereas the bidens has a prominent ridge, and depreflioii 

 on that part; bcfides, the pillar lip of this reflects upon, 

 and adheres to the body whirl, forming a fmall depreflfi- 

 on, or fub-umbilicus : in the other the pillar lip is per- 

 feflly detached, thick, and prominent. 



Chemnitz has given a bad figure of this fhell, and 

 with it a variety, which is doubtlefs no other than a 

 young bidens. 



Da Costa probablv had never feen this fpecies, and 

 has given the bidens for the young, and the T. iabiatus, 

 for the adult fhell. Linn.eus particularly fpecifies his 

 fnell to be without teeth, by faying, " Turbo perverfiis 

 Ujla turrita pcllucida, anfraclibus contrariis apertura 

 cdentula." Gmelin has certainly not given this fpecies 

 for his perverfus, as he fays, "tejla pellucida : anfraElibus 

 cojitrariis non crenatis, aperiiira tridentata. From this 

 fpecific character, as well as from the lize, which is ftated 



to 



