220 



ed longiturlinally ; apex obtufe, convoluted, canaliculated; 

 the volutions even with the body: aperture large at the 

 bafe, much contracted at the top ; the outer lip extremely 

 thin, frequently only a film, the upper part of which lies 

 clofe to the body whirl, but does not adhere until it has 

 taken almoft one volution: pillar lip a little thickened, and 

 white. Infide white; ro/wwzr//^ vifible to the end. Some- 

 times this fhell is fo exceflively thin, that it is fcarce more 

 than membranaceous, except the body part, and is not fo 

 pellucid: others are almoil tranfparent horn-colour with- 

 in and without. 



The remarkable chara6ler of this fpecies is its elafticity; 

 for though it feems fo extremely delicate, as fcarce to bear 

 handling, yet it is fo tough and flexible, that it does not 

 eafily break. Length about three-quarters of an inch; 

 breadth not quite half an inch. 



This fingular, and elegant (hell has been confounded 

 with the B. Hydatis, though fo effentially different. We 

 have feen it placed with that fpecies in more cabinets than 

 one. It is true their general habit is fomewhat fimilar; 

 but the elafticity, and external volutions of this, are at 

 once fuflficient to diftinguifh it: befides, the Columella is 

 vifible to the end in this, which is not the cafe in the other. 



Donovan has given feveral very good figures of it, 

 but of an extraordinary fize; and fays, it was difcovered 

 fome years ago on the fhores of Bawjfm Scotland; and 

 fince that, at Lvmington, and in a moat near Port/mouth. 



This 



