(3) 
Fam. 2.—USNEEI, Fr. 
‘Thallus erectiusculus, suffruticulosus, 1. passim filamentosus, varie 
dein dilatatus 1. depressus, subcartilagineus. 
We can no longer attempt to distinguish sharply as a whole, the fru- 
ticulose Parmeliacei from the foliaceous (Parmelici), and even habit, 
which binds together the former in a for the most part easily recognizable 
chain, is sometimes at fault. The genera are however well marked; and 
recent lichenographers have sought to turn these differences to account 
in the construction of higher groups. Whether they have yet succeeded 
in supplanting the older and simpler arrangement by one practically 
more useful, may be questioned; but a large amount of new and careful 
description has resulted, and this may well hereafter find expression in 
compact characters. Nylander (Syn.) has laid especial stress upon the 
anatomy of the thallus, which Schwendener, still later (Umntersuch. 1. 
supra cit. 2, p. 109) has further described in great detail. And the former 
author is here, as everywhere, the most important authority as respects 
the spermogones and their contents. 
With the exception of a single group (Alectoria, as understood by 
Nylander) the whole family belongs to the colourless spore-series. And 
of this excepted group the spores of every species except two, are also 
without colour. 
Schwendener takes the sharp difference between the symmetrically 
divergent filaments which constitute the cortical tissue in Roccella 
(Schwend. 1. c. t.6,f.2. Nyl. Syn. t. 8, f. 3) and the parallel ones of 
that of Alectoria (Schwend. t. 3, f. 14, 22) as the basis of his general 
disposition of fruticulose Lichens; and the other genera of Usneei are 
found by him to group themselves between these extremes. Usnea, as 
respects the tips of the thallus, agrees with Alectoria ; but this parallel- 
ism of the filaments disappears in the former, with the progress of ramifi- 
cation, in the older portions of the cortex ; and we find finally a confused 
network, ‘no one direction being predominant.’ A similarly confused 
tissue is more or less characteristical in Hvernia, Cetraria, and Rama- 
lina; which differ, indeed, to some extent, in the predominant direction 
of the filaments, but exhibit notwithstanding, in the majority of types 
examined, that symmetrical divergence, which indicates their approach 
to Roccella. 
The true place of Siphula, Fr., referred to his Ramalodei by Nylander, 
is in fact unknown, apothecia not having yet been seen; but the thallus 
may perhaps be said to resemble that of Spherophorus, rather more than 
it does that of Roccella. In a not dissimilar lichen of the Sandwich Isl- 
ands, described many years since by the writer as S. Pickeringii (Bot. 
Wilkes Exped. p. 124, t. 2, f. 4) what were then taken for ‘abortive 
apothecia’ are noticed, and, as figured (the specimen is not now within 
reach) may be said also to suggest the thalline receptacles of Sphceropho- 
