149 



This fingular fpecies is not uncommon in the weft of 

 England, from Dorfetjhire to Cornwall, but the lower 

 valves are feldom thrown upon the fhores : thefe adhere fo 

 llrongly to rocks, as not to be eafily feparated; and lie 

 generally in deep water: perfect fliells, however, are fonie- 

 times obtained by dredging, affixed to the infide of old 

 ovfter fliells. "* 



We have feen it perforated into thofe malTv ftones ufed 

 for fixing the mooring chains to, in Plymouth harbour ; or 

 at leaft fo enclofed, that it became neceffary to break off 

 part of the ftone to get them out. 



„ _ Obsolktus 



Peften obfoletus, Br. ZooL t. 61. f. 66. 



Don. Br. Shells, i. t. 1 . f. 2. 



Peclen parvus. Da. Cojia. p. 153. No. 7. 



Oftrea obloleta. Tart. Lbi. iv. p. 266. 



P. with numerous, fine, longitudinal ftrise, eight or ten 

 more prominent than the others, at irregular dillances ; 

 the valves are equal, and rather flat: the auricles are un- 

 equal ; one very large, fl:riated, the other extremely fmall : 

 colour dark purple. Infide fmooth, brownilh. 



This fpecies, which was firft given by Mr. Pennant^ 

 appears to be very rare. Da Costa received his from 

 the coaft of Cornwall. 



Peflen 



