55 
MYTILUS edentulus. 
TAB. CCCCXXXIX. fig. 1. 
Spec. Char. Elongated, smooth; disk obtusely 
keelshaped; beak sharp; posterior side 
nearly straight ; no tooth in the hinge. 
V ery nearly of the same form as the common Mussel, 
but the beak end i9 deeper, much more keel-shaped, and 
a little curved ; the sides are almost parallel ; the front 
is rounded, and obtuse; the hinge line straight. 
A small siliceous cast from Blackdown. 
MYTILUS lanceolatus. 
TAB. CCCCXXXIX.— 2. 
Spec. Char. Lanceolate, slightly curved, 
smooth ; disk, keel-formed ; posterior side 
flat ; beaks acute. 
A. very elegantly formed shell ; the anterior side is a 
regular sweep from the beaks to the front without any 
angle marking the termination of the hinge ; within each 
beak is one very long lamellar tooth. 
A siliceous cast found at Blackdown : it enriches the 
Cabinet of L. W. Dillwyn, Esq. and appears to be very 
rare, as only one specimen has been found. 
