GAPERS. 291 
horizontal spoon-shaped process, belonging to the 
left valve, and corresponding to a horizontal groove 
or socket in the right. The ligament is internal, 
inserted between the socket and the spoon-shaped 
process. The shell is generally white, exhibiting 
rude concentric lines of growth, and covered with 
a wrinkled epidermis, which is continued over the 
mantle and tubes of the animal. 
The mollusk, thus encased in a thick and 
leathery case, presents a close resemblance to one 
of those Tunicated Ascidiw, which I shall pre- 
sently notice, with the addition of a bivalve shell; 
‘and no better mode could be devised of impress- 
ing on the tyro in malacology the close affinity of 
two great sections, so unlike in most of their 
proper members, than the placing before him, side 
by side, examples of the genera Mya and Cynthia.” 
The species of this genus are eaten not only by 
man; Otho Fabricius informs us, that on the in- 
hospitable shores of Greenland, where they are 
numerous, they are greedily devoured by the 
walrus, the arctic fox, and by many predaceous 
birds, as well as by large fishes, 
We have two native species, both of consider- 
able size, of which the larger is the Sand Gaper 
(Mya arenaria), which attains a breadth of four 
inches, and a length of nearly two and a half. It 
is a coarse shell, of an earthy reddish or yellowish 
hue, stained with dirty black, and marked by irre- 
gular lines of growth. The animal, when its epi- 
dermis is stripped off, is yellowish-white, the 
orifices tinged with red; the investing coat is 
brown, rough, and wrinkled. 
This Gaper is common on many parts of our sea- 
shore, in gravelly, clayey, or sandy ground, at low 
