BYSSANODOIfTA. 



87 



X. SUBGENUS BYSSANODONTA. 1 



QUADRATE. 



Paranensis. D'Orb. Chenu. 



1 This is a remarkable fresh water bivalve discovered by M. D'Orbigny, remaining always attached 

 by a byssus. See Voy. dans I 'Amer. H&rid. 



