14 



covered with the coarse grass, of which domestic 

 animals as well as deer are so fond. I have observed 

 cows and hogs feeding on it with an avidity that be- 

 spoke it a luxurious banquet. Hogs will plunge their 

 heads entirely under water in search of this favour- 

 ite food. So abundant in it are the Naiades, that 

 the shells have been collected in one spot in sufficient 

 abundance, when burnt into lime, to build several 

 chimneys. Blue water creek takes its name from the 

 limestone which imparts a blue colour to its shallow 

 stream: I noticed few shells in this creek. Shoal 

 creek is similar, but "wider, and the rocks are cover- 

 ed with univalves. It is worthy of remark that the 

 shells of the Tennessee Valley differ in their general 

 character from those of the waters flowing into the 

 Gulf of Mexico; thus the Tennessee and its tribu- 

 taries do not contain Unio decisus, Lea, U. trape- 

 zoides, Lea, U. Aldbamensis, U. arctatus, nob. &c. 

 amongst the most abundant in South Alabama. The 

 head waters of the Black Warrior supplied me with 

 univalve and bivalve shells, Avhich the most patient 

 search did not enable me to find in the same river, 

 as far south as Erie, and, doubtless, like other in- 

 habitants of mountain districts, they prefer their 

 limpid streams and rocky beds to the gravelly bars 

 and turbid waters of the same rivers, where they flow 

 through an alluvial country. 



Whilst in the Tennessee Valley, I Irequently ob- 



