131 
MEGALODON. 
Gen. Char. An equal-valved, longitudinal bivalve, 
acuminated towards the beaks ; hinge a long 
external ligament, a large bifid tooth placed 
upon a septum across the beak of the right 
valve,, and one irregular and one pointed tooth 
similarly placed in .the left valve; a small pit 
near the teeth for the reception of the anterior 
ligament. 
A genus nearly related to Mytilus, but distinguished 
by the large teeth of the hinge and weight of the shell. 
It also resembles Myoconcha ; but the situation of the 
only muscular impression the specimens expose to view 
indicates its place in a natural arrangement nearer to 
Mytilus. 
