456 Lichenes of New England. 
entibus s.ex his itidem in chraumata s. initia peri- 
blastetica sensim abeuntibus." (l. c. p. 286.) 
In Great Britain, Hooker, Turner and Borrer, and 
Greville, have left entire the principal parts of the 
system of Acharius, upon which they have founded 
all their arrangement. 'The part of Sir William 
Hooker's “ British Flora ” which includes the lichens, 
is as valuable to a student of these plants in this 
country as in England. The arrangement in Natu- 
ral Families, and the admirable descriptions, princi- 
pally distinguish this work. The scaly Lecidez and 
Lecanore of Acharius, are made a distinct family, 
and constituted as three Genera. Cladonia is also 
divided into three genera, which form the family 
Cladoniex.  Borrer, it is said, refers Endocarpon to 
Verrucaria, and admits Lecanora with difficulty as 
distinct from Parmelia. But the British lichenists 
may properly be considered of the school of Achari- 
us, to which also belong those of our own botanists - 
who have illustrated the Lichenes. In the earlier 
American Floras and Catalogues a few lichens are 
enumerated. Gronovius describes several, and his 
list was somewhat enlarged by Forster, and Walter. 
The last botanist, found, it would. seem, Cetraria 
nivalis, and this was the only authority for the spe- 
cies, as à member of the United States Flora, till its 
recent discovery on the New England mountains. 
Twenty-one species, some of which are published 
as new, are given by Michaux, in his Flora. - ‘But the 
catalogue of Muhlenberg, in his Catal. Pl. Amer. 
Septent. 1818, which comprises 184 species, 18 of 
which are given as new, is the first work of impor- 
