(61) 
like the group itself generally, as compared with the other, — more richly 
differenced, and though the spores are, even more decidedly, without 
colour, soon and largely displays its real (muriform) type; a type how- 
ever, aS we have seep, not entirely without representation even in the 
genus first named. Allusion has been made to the scarcely questionable 
analogies connecting Umbilicaria as well with Sticta, as with the Colle- 
maceous lichens; but the relation in which these last stand to Pannaria 
is one, from whatever point of view we regard it, of close affinity. ——It 
is not uninteresting here to add that the modifications, whether of exter- 
nal colour, or of conditioning internal structure, which beginning in 
Sticta, and instructively exhibited in Pannaria, find their explication in 
Leptogium, recur again, in “true Lichens,” in the cephalodia (as 
explained by Nylander) of Stereocaulon. 
Pannaria is conceivable then as a decolorate member of the series 
characterized by muriform (typically coloured) spores, and as contiguous 
therefore with Umbilicaria, and, to some extent at least if not with the 
bulk of, Peltigerei on the one hand, as especially with Collemei, on the 
other. There is yet an obvious contrast between the Collemei and Pan- 
naria, in that while in the latter the greater proportion of the forms, and 
all the more typical ones, have simple spores,—the higher features of 
spore-modification showing themselves only in the receding sections, the 
confused and at length aberrant structure of which assimilates them to 
Eucollemei, it is the bulk and most typical portion of the former which 
displays the higher spore-characterization, and only, in general, the 
reduced and receding clusters in which the spores are simple. But Col- 
ema byrseum approaches the highest Pannarie as closely in its spores as 
in everything else; and Pannaria lurida makes equally significant ad- 
vances from the other direction. And so manifestly do the two groups 
run together in their inferior types, that lichenologists are unable at 
present to indicate any satisfactory characters of discrimination. 
There is some significant evidence that the simplification of internal 
structure corresponds in Pannaria, as elsewhere, with the reduction of 
the thallus. And, looked at in this light, the ill-definable generic differ- 
ences of the higher, central portions of the family before us, which forms, 
as we venture to regard it, a parallel series contiguous to Pannaria, should 
possibly seem of no higher value than the to some extent corresponding 
sectional diversities of the latter. Nor does there at least appear to 
be any doubt that the greater number of these central Collemaceous 
types coalesce most readily into a single group, or sub-family (Hucollemei) 
distinguished sharply from the still embarrassed, and, as now made up, 
at once higher and lower cluster of fruticulose and filamentous types, 
which we associate in Lichinet. 
According to the estimate of Dr. Nylander (Syn. p. 75) the whole 
number of known species of Lichens was 1361, and of Collemaceous 
Lichens 112; the proportion of the latter then being about one-twelfth. 
