MYA. GAPER. 
105 
Fabricius, in his Fauna Groenlandica, describes the Mya 
arcticaas having two somewhat spinous ridges, which are 
mostly obsolete, and with the hinge obscurely toothed, a 
character sufficiently answering to our shell. 
This species, the Mytilus mgosus, and many specimens 
of the Solen minutus where the spines are obliterated, so 
mnch resemble each other, that it is frequently very diffi¬ 
cult to distinguish them without a close examination of the 
hinge. It may however be remarked, that the Mya arctica 
and the Solen minutus both slope abruptly immediately 
from the hinge, and are each furnished with a depression 
on the slope under the hinge 3 but that the oblique dorsal 
ridge of the Mya arctica extends to the front angle of the 
opposite side, whilst in the Solen minutus this ridge usu¬ 
ally reaches about half way down the margin of the oppo- 
siteside, dividing as it were that side into two compart¬ 
ments, and giving it an angular appearance, as is well re¬ 
presented in Montagu’s figure of his Mytilus praecisus. The 
Mytilus rugosus diners from both, in not having the hinge 
close tu the end, and in having that side rounded, v. v. 
B. The teeth locking into the opposite valve. IS to 24. 
13. Mya striata. Striated Gaper. Tig * 
Linn. Trans, xi. pi. 13. f. 1 — A. 
Shell oblong, with the hack margin running nearly 
jtraigkt, very thin, semitransparent, finely striate longitu¬ 
dinally; the anterior end truncate, with the valves reflecting 
and forming a gape when the shell is closed; the posterior 
end rounded: beaks small, placed nearer the rounded end ; 
inside white, with a slight metallic lustre: hinge with a 
single broad erect tooth in one valve, locking into a cor¬ 
respondent cavity in the other: length half an inch; breadth 
an inch.. 
Found by Mr. Lyons, in Tenby bay: rare. 
19. Mya Batava. Dutch Gaper. 
Lister , pi. 146. f. 1— JV.ood, pi. 19. f. 1,2. 
Mya Pictorum. Donovan, pi. 1/4. 
Shell oblong-oval, rounded at both ends, olive green in¬ 
clining to brown, darker at the longer end, transversely 
striate. 
