' PLATE CVIII. 



MYA DUBIA. 



DUBIOUS MYA. 



GENERIC CHARACTER. 



Animal an ascidia. Shell bivalve, gaping at one end. The hinge 

 for the most part furnished with a thick, strong, broad tooth, not 

 inserted in the opposite valve. 



SPECIFIC CHARACTER 



SYNONYMS. 



Shell fragile, brown, bottom widely gaping; rudiment of a tooth 

 in one valve only. 

 Mya Dubia : testa fragili fusca subtus valde hiante valva una eden- 



tula altera rudimento dentis. 

 Mya dubia. Penn. Br. Zool. /?. 82. 19. 



Pennant, who seems to be the only author that describes this shell, 

 says it has the rudiment of a tooth within one shell; with an oval 



