456 MARINE INVERTEBRATES 
FaMILY MYIDE 
Genus Mya 
In this family we encounter, rather suddenly, some new fea- 
tures not heretofore seen in the pelecypod structure. In the 
first place, the siphons are enormously large, are united, and are 
surrounded by a leathery epidermis. The mantle-edges are fused 
together along the entire ventral margin, except for a small slit 
through which the foot may project. Although the animal may 
withdraw the long siphons into its shell, yet they remain to a 
certain extent exposed, for the valves gape widely posteriorly, 
and only slightly less so anteriorly. In the economy of these 
forms the shell seems to play a less important part than it does 
in the Veneride, in the Tellinidw, and generally in those families 
whose shells are strong and, closing firmly, afford the animal 
within a real protection. The shell of Mya (the principal genus) 
is thin, white, and of a softer chalky texture; it gapes widely 
“fore and aft,” and has a loosely constructed hinge apparatus, 
consisting of an erect projecting tooth, which fits into a pit in 
the opposite valve. — 
M. arenaria. This is the common “ soft-shell clam” of New Eng- 
land. Its range is from Cape Cod to Greenland and Great Britain. 
Upon the Maine coast it is very extensively gathered and sold to the Banks 
fishermen for bait. Its use as food for man is probably not very great, 
yet it is always to be seen on sale in the markets of New England coast 
towns. It cannot compare in flavor with Venus mercenaria, the “ hard- 
shell clam” south of Cape Cod. M. arenaria lives between tides in 
muddy, sandy, peb- 
bly, or even rocky 
ground, where it 
can find material in 
which it can burrow 
and hide itself. It 
lies just below the 
surface, with its si- 
phons projected into 
the water. When 
the water recedes, 
Mya draws in its si- 
phonsand awaits the 
return of the tide, 
Mya arenarva, every now and then 
