20 
etc., it is stretched. -In Mya there is an erect, spoon-shaped 
process in one valve, for the attachment of this cartilage, and 
‘ 
Fig. 18. Mya arenaria. 
a triangular pit in the other valve. The valves gape at each 
end of the shell; the siphons of the animal are very long. 
Fig. +5. P aedaiea solidissima. 
The Beach Clam family, Mactride, have the eortiinas pit 
of the same form in both valves, and on’ each side of it there 
—s 
