506 



PROCEEDINGS OF THE NATIONAL 



species are South American. The following list shows the number of 

 species in each genus and the distribution of the genera: 



Margaritana, Circumboreal. 

 Unio, North America, Palearctic. 



13 varieties. 

 Pleurobema, United States. 



1 variety. 

 Quadrula. North America, Eastern 



Asia. 



12 varieties. 



Schistodesma, Eastern Asia. 

 Gibbosula, Eastern Asia. 

 Cuncopsis, Eastern Asia. 

 Nodularia. Eastern Asia. Asia Minor, 



Tropical Africa. 



6 varieties. 



Harmamlia, Southeastern Asia. 

 Physunio. Southeastern Asia. 

 Dalliella, Southeastern Asia. 

 Grandidieria, Tropical Africa. 

 Pseudodon, Eastern Asia. 



1 variety. 



Parreysia, Southeastern Asia, Tropi- 

 cal Africa. 



8 varieties. 

 Ptychorhyuchus, Eastern Asia. 



1 variety. 



Virgus, Southeastern Asia. 

 Ctenodesma, Southeastern Asia. 

 Rectidens, Southeastern Asia. 

 Lamellidens, Southeastern Asia, 



Tropical Africa. 



5 varieties. 

 Trapezoideus, Southeastern Asia. 



1 variety. 



Arcouaia; Eastern Asia. 



Pseudavicula, Tropical Africa. 



Arcidopsis, Southeastern Asia. 



Tetraplodon, South America. 

 1 variety. 



Castalina, South America. 



Callouaia, South America. 



Hyria, South America. 



Prisodon, South America. 



Diplodon, South America, Austral- 

 asia, South Africa. 



6 varieties. 



19 Truncilla, United States. 6 



3 varieties. lir> 



2 Micromya, United States. 



8 varieties. 



128 Lampsilis, North America. 

 4 Pseudospatha, Tropical Africa. 99 



10 Hyriupsis, Kastern Asia. 

 ' 3 Chamberlainis, Southeastern Asia. 

 10 Cristaria, Eastern Asia. 2 



2 Lepidodesma, Kastern Asia. 1 



4 Ptlsbryoconcha, Southeastern Asia. 5 



6 Medionidus, United States. 90 



22 Nephrouaias, Mexico, Central Amer- 

 ica, Cuba. 



1 Ghjbula, United States. 

 9 Ohovaria, United States. 



1 variety. 7 



8 Pliigiola, North America. 11 



2 Tritogonia, United States. 23 



1 variety. 



2 Cyprogeuia, United States. 38 



1 variety. 

 1 Obliqnaria, United States. 



6 Ptychobrau'chus, United States. 



8 Strophitus, North America. 



1 variety. 



55 Auodonta, North America, Eastern 2 

 Asia, Palearctic. 5 



8 varieties. 12 



4 Colletopterum, Southeastern Europe. 



3 Gabillotia, Asia Minor. 



1 variety. 5 



7 Leguminaia, Southern Europe, Asia 



Minor. 3 



1 variety. 1 

 1 Lastena, United States. 1 



9 Solenaia, Eastern Asia. 9 

 1 Gonidea, United States. 



1 Anodoiitoides, North America. 5 



2 varieties. 1 

 1 Pegias, United States. 4 

 1 Arcidens, United States. 8 

 7 Syruphyiiota, North America. 94 



1 variety. 



13 Alasmidouta, North America. 

 1 Hemilastena, United States. 



MUTELID.K. 



27 Spatha, Tropical Africa. 



3 Varieties. 

 9 Mutela, Tropical Africa, 



2 Chelidouopsis, Tropical Africa. 

 5 Brazzeea, Tropical Africa. 

 4 Pleiodon, Tropical Africa. 



