( iv ) 
structure, of the last thirty years, justify the newer dispositions of the 
system in their departures from the older; and to what extent are the 
latter still adequate to the phenomena, and, for the present, preferable. 
The author has at least had some occasion to approve of the arrangement 
here set down, in his own studies, as in the requirements of teaching ; 
and its excellence is by no means lessened, in his eyes, that it is readily 
intelligible. 
It is admitted indeed, and by all but universal consent, that Lichens 
may be said to fall into two principal series, determined by ground-differ- 
ences of the apothecia:—a naked-fruited (Gymnocarpous) series, of 
which the type is the dish-like apothecium, and a covered-fruited (Angi- 
ocarpous) series, of which the type is the mammiform apothecium. The 
second series, inferior in all respects to the first, offers only distinctions of 
very subordinate value, in the process of differentiation of its type; 
which yet is so marked, that these lichens (Verrucariace’) are kept 
together by all authors. In the first, however, which embraces the great 
mass, and the highest exhibitions of lichenous vegetation, the various 
modifications of the dish-like (patelleform) fruit are, in their turn, enno- 
bled; and prove to possess a systematic importance unexplained certainly 
by their anatomical. We appear to be indicating but moderate, and now 
even slight deviations when we say that the patelleform exciple of Bia- 
tora being diminished (mostly) and hidden or bordered by an accessory, 
thalline receptacle becomes thereby scutellzeform ; — or simply elongated, 
lirelleeform ;— or stalked (for the most part) and the disk, at the same 
time, so to say, disorganized, and consisting of naked spores, crateriform ; 
but these differences are indications, none the less, of four great assem- 
blages, or tribes, of Lichens; assemblages which, however modified, or‘ 
even perpiexed, the first two may be in his classifications, no lichenogra- 
pher entirely ignores, and no lichenist can afford to neglect. All lichens 
are then, in this view, either 1, Parmeliaceous, 2, Lecideaceous, 3, Graph- 
idaceous, 4, Caliciaceous, or 5, Verrucariaceous. The student will find 
sufficient perplexities; but the advantage to him of the comparative 
simplicity of this first step into the system is manifest. 
It appears moreover incorrect to contrast disadvantageously the 
arrangement to which we have just referred, with some later ones, as if 
the former were artificial, and the latter, so to say, natural.. With what- 
ever attempt at an universal view nature be pursued, art must supervene, 
would we bring knowledge to a practical systematic form; and the 
