514 



PROCEEDINGS OF THE A A 77 O.V.I/. MUSEUM. 



r r 



>. 



(Heterof/enw.) 



Female shell inflated at base in 

 front of posterior ridge; marsupiuiu 

 in hinder part of outer gills. 



SYNOPSIS OF THE (1ENERA OF NAIADKS. 



Trtincilla 



Micromya Agassiz. 

 LampsiUs Rafinevqne. 

 Pseudospatha, Simpson. 

 Hyriopsis Conrad. 

 Chamberhtinia Simpson. 

 ( 'rixtarid Schumacher. 

 Lepidodcsma Simpson. 

 Pilsbryoconcha Simpson. 

 Medionidus Simpson. 

 .N>/j/irofliaCrosse and Fischer. 

 Gli'bula Conrad. 

 Oboraria Rafinesijuo. 

 Plaf/iola Rafinesqne. 



Female shell inflated behind, Tritogonia Agn^l/.. 

 above posterior ridge. 



f (Mesogenw.) , 



i <'yprogenia Agassiz. 



Marsupium a few ovisacs in the< Qbliquaria Rafinesqne. 

 center of outer gills. 



Marsupium occupying the whole 

 outer gills in a series of folds. 



(Exchatiyenw.) 



Marsupium occupying the outer 

 border of outer gills. 



(Diagena'.) 



Ovisacs filling the outer gills, 

 running crosswise. 



Piychobranclnix Simpson. 



Dramas Simpson. 



Rafinesque. 



Anodonta Brugniere. 

 CoUetopterum Bonrguignat. 

 Gabillotia Servain. 

 Lcguminaia Conrad. 

 Lasiena Rafinesque. 

 Solenala Conrad. 

 Gonidea Conrad. 

 Anodonioides Simpson. 

 Pegias Simpson. 

 .trcidens Simpson. 

 Symphynota Lea. 

 Alasmidonta Say. 

 Hcmilastciia Agassiz. 

 Margaritana Schumacher. 

 I 'nio Retzius. 

 [ Pleui-obema Rafinesque. 



( Tetragena.-) , Quadmla Rafinesqne. 



Marsupium filling all four gills, J Schistodesma Simpson, 

 forming smooth pads; beak cavi- ) GibbosuJa Simpson, 

 [ties deep. [ Cuneopsis Simpson. 



(Homogenn'.) 



Marsupium filling the entire 

 outer gills and forming smooth 

 pads. 



