4G3 



ly, but is flatter, and not fo convex on the upper part, 

 and is at once diftinguifhed from that fiiell in not pof- 



fefTin^r thofe lines which mark the concamerations. 



o 



It was firft noticed by Mr. Agnew, gardiner to the 

 Dutchefs Dowager o^ Portland; and was given in the 

 Pliilofophical Tranfadions o^ I'jSG by Mr. Lightfoot, 

 who ftates it to be met with in clear waters in the neisjh- 

 bourhood of BulLJlrode in BuckinghamJJiire. 



We have found it fparingly in the ditches about Ware- 

 ham in DorfetfJiire : and near the village oiWedhampton 

 in WiUpdre ; but have obferved it in greater abundance 

 in a fifli-pond at Lackham in the fame county, and in 

 the river contiguous, adhering to aquatic plants ; fre- 

 quently deep in the water. 



It appears to be a local fpecies, and not very plenti- 

 ful any where ; though v/e are informed it is not uncom- 

 mon about Sandzoick in Kent ; from \vhence we were 

 favoured with it by Mr. Boys. 



Animal light chefnut : tentacula two, long, flender, 

 ■filiform, lighter coloured than the body ; eyes placed on 

 the upper part of the head at their bafe: head long; 

 fujlentaculum Ihorter than the tentacula. 



From the extreme pellucidity of the fhell, a ftrong 

 and regular pulfation is obfervable (by the afliftance of 



a cum- 



