138 ON THE NAIADES, 



impressed with the character of those of the lake. In this river there 

 is, however, little to my knovs'ledge interesting to the conchologist. 



Lake Champlain, M^hich empties its waters into the St Lawrence, 

 is prolific in some of the western species. The Symphynota alafa, the 

 Unio occidens and the Uhio rectus, with some other western species, 

 are found there in great perfection, but none of the tuberculated or 

 undulated species. 



The southern extremity of the Alleghany ridge is supposed to reach 

 into the upper part of the state of Alabama, where it terminates by 

 spreading out into high lands east of the river Tennessee, and near to 

 that part where the river makes its most eastern angle. The sources 

 of the Alabama and Tombeckbee rivers, which discharge themselves 

 into the Gulf of Mexico, are situated in these high lands, and the char- 

 acter of the shells of these rivers is completely the same with those 

 of the western waters. In no instance have I observed a shell from 

 these rivers, or the Mississippi, which possessed the characters of those 

 of our eastern rivers. To draw the exact line of distinction here, in 

 the present state of our knowledge, is impossible ; but that such a line 

 does exist there can scarcely be a doubt. 



The great difficulty experienced by naturalists in procuring speci- 

 mens from newly settled and distant parts of the United States is such, 

 as to deprive us of much desirable information. This impediment 

 will, it is hoped, be overcome in time, and the natural history of our 

 country become universally known. 



In the present state of our knowledge, we can only place this line 

 somewhere between the Alabama and the Altamaha rivers. From 

 the latter, I have seen but a single valve, which I owe to the kindness 

 df Mr Nuttall. This is the U. complanatus (Soland.), and marks dis- 

 tinctly the character of the shells of this river to appertain to that of 

 the eastern waters. From the river Appalachicola I have never been 

 able to procure a single specimen, and it remains yet to be proved 

 whether it produces shells of the eastern or western character. As, 

 however, it disembogues in the Gulf of Mexico, it is more than proba- 

 ble that it possesses the same species as the western waters, and its 

 neighbour the Alabama. 



In regard to the shells of the soil, it will naturally be asked if they 



