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 
theshells 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, Lua, U. Alabamensis, U. arctatus, nob. &e. 
amongst the most abundant in South Alabama. The 
head waters of the Black Warrior supplied me with 
univalve and bivalve shells, which 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, | frequently ob- 
