Oe a arr = 
m. 
aptain Mackay informed me, he had seen a few tufts 
of dwarfish grass; but as this is rare, it may have been 
introduced by some visitor or from some ship. 
According to’ this View of the matter, the Flora of this 
new world consists of a single species; which I hope you 
will be very particular in deseribing. 
While I thus lay before you this interesting production, I 
-congratulate you on the receipt of numberless other produc- 
tions from foreign climes, which our spirited navigators are 
incessantly presenting tous! 0 8 
S (838 -tieoases J f : 
The specimens presented to me by Dr. Mitchell, evident- 
ly belong to a species of Lichen. Several of them were 
covered. with small tubercles very much resembling the fruit 
of Roccella, which, with the habitat of the plant, induced me 
to refer it to that genus. Ona closer examination, howev- 
er, I have no aati of its being a species of Usnea without 
the proper fruit, merely having the cephalodia which are not 
uncommon in U. florida, &c. It has the central hyaline 
thread, so constant and important a character in this genus. 
According to Acharius, all the Usnew are found exclusively 
on trees: so that this species, which grows on rocks appears 
to form an exception to all the rest. In the Flore Francais, 
however, the U. florida is said to occur sometimes an rocks 
and the U; articulata on the ground. The present species 
does not appear to be described in the Synopsis Methodia 
Lichenum of Acharius; Ihave therefore considered it as 3 
new oné, and have called U. fasciata. 
_ USNEA Acuarivs. 
Recerracutum wniversale subcrustaceum  teretiuscu- 
lum, ramosum plerumque pendulum, fasciculo ductulorum fi- 
liformi elastico centrali hyalino percussum, Partiale orbi- 
Vor. No. I. 14 
