Tue following pages are designed to contain brief de- 
scriptions of all the Musct and Hepatic hitherto detected 
in that portion of the United States lying east of the 
Mississippi River. A few species found elsewhere, either 
new, or having a geographical range hertofore unnoticed, 
or for some other special reason, have also been described ; 
namely, those from Texas and New Mexico, and also 
several from near our northern boundary, and likely to 
occur within it. 
The territory within the limits adopted—extending, as 
it does, from 25° to 47° North Latitude, and traversed for 
nearly its entire length by mountain ranges, reaching, at 
several points in their northern and southern terminations, 
an alpine elevation—presents conditions favorable to a 
copious and varied muscological vegetation. And if the 
number of species here recorded is not so large as that 
found in an equal area similarly situated on the Eastern 
Continent, it must be borne in mind tkat our Bryology 
and Hepaticology (particularly the latter) have thus far 
been very imperfectly investigated. Scarcely any portion 
of our country, excepting Central Ohio, has been carefully 
examined. The mountain ranges have only been cursorily 
visited by a few interested in these branches of Botany. 
In the northern section, notwithstanding numerous dis- 
coveries made by the late Mr. Oaxss, and the more re- 
cent ones (among them a Dichelyma,a Tetrodontium, and 
