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PERNA, 
Perna, Lamarck, &e. 
Ostrea, Linné. 
CHARACTER GENERICUS. 
Testa bivalvis, compressa ; cardo transversim aut obliqué 
sulcatus; sects linearibus, parallelis; /igamentum elas- 
ticum. 
ANIMAL byssoferum. 
PERNA. 
GENERIC CHARACTER. 
Shell bivalve, compressed ; hinge transversely or obliquely 
sulcated ; grooves linear, parallel ; ligament elastic. 
Anmmat furnished with a beard. 
The Perna inhabit the sea ; they adhere to different bo- 
dies by their beard: of their natural history nothing is 
known. They are sometimes named grate-shells, and some 
species occur in a fossil state. 
