(60 ) 
There is no doubt, as respects the great bulk of Usneei, Parmelici, 
and Lecanorei, that these groups are most readily conceivable as contigu- 
ous sections of a single series (Fr. L. H. p.15) whether we regard external 
characters or those derivable from the spores ; but the case is scarcely as 
clear with respect to the frondose-foliaceous Parmeliacei, the (typical) dif- 
ferences of which in form might be taken to be corroborated, to some 
extent, by the spore-characters, as they are at length also by important 
ones in thalline structure. Thus regarded, Umbilicariet,—the spore 
type of which, no less than its abnormally conditioned apothecia, separate 
it from Parmeliei, notwithstanding the close affinity of the two groups as 
expressed in Omphalodium Pisacomense, Mey. & Flot.,— would appear 
as the first marked member of another series, continued by Sticta and 
the other Peiltigerei, passing through important changes in Pannariei, 
and finding its extreme point in Collemei. Umbilicaria, comparable in 
structure with the highest Collemei in everything except the gonidia, 
would thus begin a line including (as we understand it) all its most evi- 
dent analogues; and suggest as well the real position of Sticta. Nor 
should the fronds of Paulia and Omphalaria seem less significant, in this 
connection, than the gwasi-Collemaceous fruit of the cited Omphalodium. 
The difficulties in the spore-character of the Peltigerei, which might well 
seem, as we have taken them, despite the everywhere traceable indica- 
tions of colour, becoming at length distinct, to be rather referable to the 
colourless series, would thus, in like manner, be possibly lessened; and, 
— those of the certainly contiguous Pannariei being explained by Col- 
lemei, mouch as Sticta by Umbilicaria, —Pannaria, etc., would be re- 
moved from a place (the colourless series, represented by the bulk of 
Usneei, Parmeliei and Lecanoret) less really related to them, to one not 
unsatisfactory. The distinction in the spore-characters of Pannaria, as 
here understood, and Hucollemei, is mainly that that of the latter is, — 
schichtige Thalle, Wallr., Martius, etc.) et en thalles hétérogénes (wngleichschich- 
tige oder heteromerische Thalle). Car les Collema qui, suivant M. Wallroth, 
devraient former a& eux seuls la premiére classe, sont loin @offrir des frondes vrai- 
ment homogénes ou similaires, et ne sont point davantage privés absolument, 
comme la prétendait M. Martius de couche grenue verte ou gonimique (griine 
Kernerschicht;) si, en effet, ainsi que nous Vavons vu, la matiere verte est chez 
quelques unes dissoute dans le mucilage de la fronde, chez un plus grand nombre 
elle est concentrée en globules, qui pour étre réunis en chapelets, ou quelquefois 
dispersés, sans ordre apparent dans toute Vépaisseur du thalle, n’ent semblent 
pas moins des organes analogues aux gonidies des autres Lichens.” Tul. sur 
les Lichens, p. 30, tab. 6,7,9. “On peut faire remarquer ici que les Lichina, 
qui ont été souvent mis au nombre des Algues marines, et auxquels M. Fries et 
plus récemment M. Scherer ont refusé une place parmi les Lichens d@ Europe, 
en décrivant ou énumérant ces végétaux, que les Lichina, dis-je, possédent 
au contraire, dans un degré élevé, tous les caractéres qui distinguent les 
Lichens; il suffit pour s’en convaincre de rapprocher des détails qui précédent ce 
que nous avons dit plus haut de leurs apothécies et de la structure de leur thalle.” 
Ibid. p. 188, 
