21 



a tube, whofe bore is ovate, with an internal rib on each 

 fide, adapted to the grooves formed by the junction of the 

 animals fyphons, which are connefled their whole length, 

 and are as long as the fheil, confequently extend far beyond 

 the tube in fearch of food. This ftruflure is fomewhat 

 fimilar to that of Teredo Gigantea, reprefented in the Philo- 

 JopUcal TranfaEtions for 1806, Tab. 10, Fig. 3 — 5. but that 

 the ribs do not join and form two diftincl tubes by a feptiim. 



We have fpecimens of this Mya, in common lime ftone, 

 in fluor, and in granite. How the filiceous part of this laft 

 is dellroyed, we do not pretend to determine. Can the 

 animal difcharge the filiceous grains whole through its tubes 

 when the calcareous, micaceous, or other more foluble con- 

 ne6ling parts are foftened; or does it prepare a menftruum 

 fimilar to fluor acid, and thus effedl the deftrucftion of the 

 whole ? 



Shell ovate, flightly wrinkled tranfverfely, and of a purple Purpurea. 

 colour about the umbo, fhaded to a white towards the 

 margin : umbo placed confiderably to one fide, and turning 

 towards the fliorter end. Infide paler, and the margin plain : 

 hinge with a fingle ere6l tooth in each valve, flghtly bifid. 

 Length not above one line, and fomewhat more in breadth. 



Taken amongft coralline in desp water : Devon coafi, 

 very rare. 



Shell 



