50 



'oval. 



ANODONTA 



r 



Alas, edentula. Say. 



An. areolatus. Swain. Coop. Linsl. 



An. unadilla. Dekay. 



* Cumingii. Lea. 



*pavonia. Lea. Dekay. 



*limnoica. If Orb. 



trigona. 1 Spix. D' Orb. Kiist. 



purpurea. Valen. 



*Ferussaciana. Lea. Dekay. 

 Alas. Ferussaciana. Kiist. 



*denigrata. Lea. 



*oblita. Lea. 



*argentea. Lea. 



*ferruginea. Lea. 



*salmonia. Lea. 



*inibecillis. Say. 

 An. incerta. Lea. Kiist. 



*irnplicata. Say. Gould. Linsl. 

 Migh. Dekay. Stimp. 

 An. Newtonensis. Lea. 

 An. excurvata. Dekay. 



*fluviatilis. Lea. Gould. Adams. 

 Linsl. Dekay. 



Myt. fluviatilis. 2 Dill., not Gmel. 



Wood. 

 Myt. illitus. Soland? 

 An. cataracta. Say. Sow. Kiist. 



Migh. 

 An. marginata. Say. Adams? 



Linsl. Migh. Stimp. 

 An. teres. Con. 

 Unio cataracta. Desh. 



*opaca. Lea. 



*crepera. Lea. 



*Arkansensis. Lea. 



*Mortoniana. 3 Lea. 

 An. Chiquitana. D'Orb. 

 Craspedodonta smaragdina? Anton. 

 Kiist. 



*glauca. 4 Valen. 

 An. glauca. Lam. 

 An. ovatus. Swain. 



*plana. Lea. Dekay. 

 An. declivis. Con. 



*decora. Lea. 



*Harpetliensis. Lea. 



*gigantea. 5 Lea. 



*subvexa. Con. 



1 Ferussac considered trigona the same as crassa of Swainson. The two figures, however, appear to me to be 

 too different to be considered the same. 

 3 See note on An. cygnea. 



3 D'Orbigny gives An. trigonum, Spix., as a synonym. 



4 The figure of this shell resembles some individuals of Myt. fluviatilis, Soland. (Say's An. cataracta), but is 

 straighter on the superior margin. In this character it resembles the trapezialis. The observations of Barnes, 

 being made when little was known of this genus, cannot now be admitted. 



5 An. giganteus, Spix., having been before described by Lamarck under the name of trapezialis and exotica, 

 my species must retain this name. 



