100 
MYA. GAPER . 
which we have very little doubt is this species of a smaller 
size, but which it has not been our good fortune to exa¬ 
mine. We consider it however as an interesting subject, 
which may serve to establish or annul our suspicions as to 
the distinctions we have made between this species and the 
last. v. v . 
5. Mya Norwegica. Norway Gaper, Ri^./oo. 
Wood; pi. 18. f. 4,5. 
Shell thin, brittle, transparent, convex, oblong-oval, 
white but not glossy, and covered when fresh with a fine 
brownish white skin, marked with numerous fine regular 
raised longitudinal striae, and a few transverse wrinklesj 
one valve rather smaller than the other, and as it were re¬ 
ceived within it; the larger side rounded,the otherorjm- 
terior side sloping from the beaks, and running in nearly 
a straight direction to the end, where it is truncated, very 
rugged, with the valves gaping and a little reflected; the 
front margin produced and rounded: beaks prominent, 
pointed, nearly central: inside richly nacred: hinge with 
a rather oblique triangular striated cavity in each valve: 
length three-quarters of an inch; breadth more than one 
and a quarter. 
A fresh and perfect specimen of this rare shell wa 
dredged up off Exmouth, in the present summer, and is 
now in the possession of Mr. Leasathorp, who obligingly 
suffered us minutely to examine and describe it. It had 
no decortication about the beaks, as mentioned in the spe¬ 
cific character of Gmelin. and Dillwyn, and which might 
have originated in an accidental abrasion of the fine epi* , 
dermis or pellicle. The longitudinal strix appear to be 
formed by regular corrugations of its outer skin, which at 
the smaller and gaping end enlarge into rough membrafla* ; 
ceous folds. From the Mya striata it is distinguished byits r 
greater convexity, the teeth, the produced and rounded out- | 
line of the front margin, and the narrowed truncated end | 
which resembles that of the M. declivis. v. m. 
6. Mya convexa. Convex Gaper . 
Wood, pit 13. f. 1. 
£!ya declivis* Donovan, pi. 82. 
. ; - feheij ; 
