SYNOPSIS 



THE FAMILY OF NAIADES. 



The following table of arrangement and synonymy was undertaken purely with the 

 view, and in the hope of clearing away the difficulties which had incumbered one of the 

 most interesting families of the Mollusca. In this attempt I met, while pursuing the task, 

 with obstructions and difficulties which I little anticipated at its commencement. The 

 want of some of the books of reference, and the confusion which reigned throughout many 

 of them, sometimes presented obstacles which seemed almost insurmountable. The exten- 

 sive and admirable library of the Academy of Natural Sciences of Philadelphia has greatly 

 aided me in this edition. In attempting to establish the synonymy, I have endeavored to 

 render the strictest justice, and if, in any case, it be found that I have failed to do this, it 

 will be a matter of sincere regret. All corrections will be greatfully acknowledged. 



In the following tables there will be found in the family, 539 recent species as 

 admitted, 127 unknown to me or doubtful, and 106 fossil; in all 767. 



Of the subgenus Triq-uetra (Klein), 1 there are 3 species. 



Of the subgenus Prisodon (Schumacher), 2 2 species. 



Of the subgenus Unio (Retzius), there are 401 species in a recent state, and 84 which 

 I have not been able to admit as certain; of fossil species 97. 



Of the subgenus Margaritana (Schumacher), there are 18 admitted species, and 3 

 which are unknown to me. 



Of the subgenus Monocondylcea (D Orbigny), there are 8 species. 



Of the subgenus Dipsas (Leach), I know of but 2 species, both of which are recent. 



Of the subgenus Anodonta (Cuoier), there are 90 admitted species, and 39 which are 

 unknown to me. Of fossil species there are 9. 



1 Tentamen Meihodi, 1753. 



2 Nouveau Systhme, 1817. 



