27 
MYTILUS. 
Gen. Char. Bivalve longitudinal shell with an 
acute base; beaks straight,, nearly acute^ ter- 
minal; hinge mostly toothless. 
MYTILUS am plus. 
TAB. VII. 
Spec. Char. Shell depressed^ triangular, acute- 
angled at the base ; longitudinally striated^ ex- 
cep ting over the posterior side ; thin. 
Almost twice as long as broad, depressed, triangular, 
length of the two sides unequal, two of the angles rounded, 
the third at the base acute. Valves acutely convex towards 
the base, with a slight curve; striae impressed, arising from 
the beaks, and proceeding with some undulations to the 
extremity of the shell. Posterior side straight, a little 
waved, free from striae. The shell very thin, and com* 
posed of fibres perpendicular to its surface. 
I am obliged to my kind friend, Thomas Meade, Esq. 
for procuring me this specimen from the Limestone quarry 
at Mitford. It is worthy of remark, that this shell at first 
sight resembles a Pinna, it does not, however, appear even 
to have been open at the extremity, or gaping at the upper 
part, as the Pinna is. 
