32 



river, and in the rivers of States westward ; while on the 

 other hand, Unio Boykinianus is found in the Chattahoo 

 chee and Alabama rivers, and probably, also, in some of 

 the rivers of Mississippi. Unio obtwus, found in the Chat- 

 tahoochee, also occurs in Mississippi, while a species of 

 similar form, U. Claibornensis, takes its place in the Ala- 

 bama river. 



Unio infucatus and U* Kleinianus are said to occur in 

 the Chattahoochee river and its tributaries in Georgia, 

 while no -available record exists of their having been found 

 in the streams rising in Alabama. 



Unio lienosus, found in Mississippi and various streams 

 in Alabama, seems to be replaced in the Chattahoochee 

 system by three well defined species of the same group, 

 viz : U. concestator, U< intercedens and U. fallax. 



Unio crassidens, a robust species found in Illinois, Ohio, 

 Kentucky, Tennessee, and also in the Alabama and Coosa 

 rivers, in Alabama, is replaced in the Chattahoochee and 

 Flint rivers by a nearly related species U. incrassatus. 



Unio camptodon (and Unio tetralasmus, possibly a syno- 8 

 nym,) occurs in Ohio, as well as in Alabama, Mississippi 

 and Louisiana.- Unio ColunibensiSj of the Chattahoochee, 

 seems to unite camptodon with declivis, forming a group. 



Unio atro-costatus, which is often taken to be U. perplica- 

 tus, Conrad, seems to take the place of that species in Ala- 

 bama. There is no reliable record that perplicatus occurs 

 so far east as Alabama. 



Unio Blandianus, of the Othcalooga creek in Georgia, is 

 represented in Alabama by shells which are regarded as 

 being U. Rumphianus. If the two should prove to be iden- 

 tical, Blandianus will rank as a synonym of Rumphianus. 



Unio penitus, of the Alabama river,- is replaced further 

 east (in Alabama and Georgia) by U. compactus, a similar 

 but smaller species. It is possible that both these species 

 occur in the Coosa river ; but at the present time a doubt 

 is entertained of such occurrence. 



Unio castaneus, of the Alabama river, is the analogue of 

 U. circulus of Tennessee and Ohio. Specimens are some- 



