34 



In the tributaries of the Chattahoochee river occur sev- 

 eral species which belong to the " complanatus group" & 

 group which includes a large numbe'r of species, of which 

 Unio complanatus is a familiar type. This group of shells 

 prevails in the rivers of the Atlantic slope, and very few 

 members of this group occur west of the Chattahoochee 

 drainage. A single instance may possibly present itself in 

 a species known as Unio sublatns, specimens of which have 

 been found at or near Montevallo. It is possible, however, 

 that sublatus really belongs to a group of which U. gibbosus 

 is almost the sole type, (Unio subgibbosus being the excep- 

 tion.) The specimens referred to have the peculiar dark 

 riacre and the singularly undulated breaks of U. gibbosus, 

 though differing from that species in the form of the teeth, 

 and in the details of the muscular and palleal cicatrices. 



There remain abundant suggestions which might possi- 

 bly be profitably added, but as this would necessarily involve 

 much descriptive matter, it is deemed expedient to refer the 

 student to the published writings of Isaac Lea, LL. D., in 

 which will be fouud descriptions of a very large share of 

 the Mollusca of North America, with usually very fine 

 illustrations. The writings of Thomas Say, Mr. T. A. Con- 

 rad, Mr. John G. Anthony, Dr. Barnes, Hildreth, and oth- 

 ers, might also be read with advantage. 



Notes on COBBIOUIVAD^;. 



Cyrena Garolinensis is found on the Atlantic coast as far 

 North as South Carolina. It occurs also on the west coast 

 of Florida, and has been tabulated here on the presump- 

 tion that it will unquestionably be found in Mobile Bay. 



Shells referable to Sphcerium stramineum, found in Ala- 

 bama, are quite unlike any thing from other States that 

 have been presented as that species. 



A single specimen, only, of 8. f abate is all that has been 

 presented from Alabama. 



Sphcerium occidental was found prv>r to 1860 in a swamp 

 near Columbus, Ga.; whether in Alabama or Georgia is un~ 

 known. It will undoubtedly be found in similar situations 

 in Alabama. 



