doubly exceed the length, are almod cyiindric, and very 

 convex ; many are flat and greatly diOorted ; yet, not- 

 "withllanding fcarce two are found alike, the rpecific cha- 

 rafters are Urongly marked. Worn (hells are fometimes 

 purple on the outlide as well as within. 



This fpecies perforates the hardeil lime-ftone, where it 

 is fometimes lodged in great abundance : we have found 

 detached pieces of fuch ftone thrown upon the coaft of 

 Devonjhire, efpecially about Plymouth, perforated like a 

 honey-comb, with theie (hells in it. It is alfo found in 

 fome parts of Cornwall. 



Do6lor PuLTENEY fpcaks of it as plentiful on the Dor- 

 Jet coaft in clay, as well as in lime-ftone. It rarely ex- 

 ceeds half an inch in length ; and three-quarters in breadth. 



Da Costa has quoted the Tellina cornubienjis of Pen- 

 nant, and BoRLASE for his PeElunculus truncatus, in 

 which he has certainly erred ; and indeed his (liell (eenis 

 to bem perlefl obfcurity. The general defcription might 

 anfwer very well for a worn fpecimen of the Donax Irus, 

 hui the margin being notched forbids it. 



GEN. 



