4 Ve CLASS IX. ORDER IIt 
ORDER 3. BIVALVA. 
Soft animals, having shelis with two valves. 
Mya, (pearl-muscle, gaper,) animal an ascidia; 
shell bivalve, generally gaping at one end ; hinge 
with broad thick strong teeth, seldom more than 
one, and net inserted into the opposite valve. 
SoLeEN, (razor- sheath,) animal an ascidia; shell 
bivalve, eblong, open at both ends; hinge witha 
subulate reflected tooth, often double, and not in- 
serted in the opposite valve. 
TELLINA, animal a tethys; shell bivalve, gen- 
erally sloping on one side ; in the forepart of one. 
valve a convex, of the other a concave, fold; hinge. 
usually three teeth, the lateral ones smooth in one. 
shell. 
Carpivum, (cockle,) animal a tethys ; shell bi- 
valve, nearly equilateral, equivalve, generally 
convex ; longitudinally ribbed, striate or grooved, 
with a foathed margin ; hinge with two alter rate 
teeth near the benk 1 in the prdille, and a larger re- 
mote lateral one each side, each locking into the 
opposite. 
‘Macrra, animal a tethys; shell bivalve, une- 
qual sided, eqnivalve : middie tooth of the hinge 
complicated, with a small hollow each side, late- 
ral ones remote and inserted into each other. 
Donax, animal a tethys; shell bivalve, with 
generally a crenulate margin, the frontal or ante- 
rior margin very obiuse ; hinge with two teeth, 
and a single marginal one place da little behind, 
which is rarely double, triple or none. 
Venus, (common clam,) animal a lethys ; shell 
bivalve, the frontal margin flattened with incum- 
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hilt 
