(185 ) 
Buellia oidalea is far more perfect than anything described in the Lecan- 
oreine genus. 
There are sixty odd described forms of Buellia ; differing however no 
little in probable rank. Of these, three fourths are European, and com- 
paratively few, except the almost cosmopolitan B. parasema, lactea, and 
geographica, have been recognized beyond Europe and North America. 
It is yet to be presumed that a much wider extension awaits the saxico- 
line groups. Scarcely half of the European forms (reckoning here, as 
above, not a few which we cannot regard as species) have been detected 
within our limits; but we possess several peculiar to the country. 
The effigurate section of Buellia, as known in the northern hemisphere 
(Catolechia, Flot., Anz.) consists of species with bilocular spores, which 
are connected most readily, and, as in the corresponding sections of 
Lecanora, Biatora, and Lecidea, by the spermatia as well, with the group 
(Buellia, Auct. pl.) with uniform thallus. But we have to interpose here 
a yellow, areolate, but marginally lobulate lichen from the Cape of Good 
Hope, —B. Africana (Lecidea, Tuck. Obs. Lich.1. c. 4, p. 406) —the spores 
of which are thrice septate. The crustaceous species with uniform thallus 
(ELubuellia) run through, on the other hand, the whole series of modifi- 
cations of the coloured spore: culminating, in the corticoline group, in 
B. albo-atra and B. oidalea ; and, in the saxicoline, in B. geographica. 
Of the effigurate section (Catolechia) we possess four of the six species. 
B. epigea (Pers.) (Scher. Lich. Helv. n. 299. Rabenh. Lich. Eur. n. 343) 
has occurred, on the earth, in company with Placodium fulgens, in the 
‘bad lands of Judith,’ Nebraska, and on the North Platte (Miss. and 
Yellowstone Exp.) Prof. Hayden. ——B. radiata, Tuck. (Lich. Calif. p. 25) 
is an areolate species—the areoles either passing into a lobulate margin, 
or the margin, in another form, reduced to a black, hypothalline fringe. 
Apothecia of Diplotomma, as Flotow understood it, and often strikingly 
lecanoroid, but the finally convex and pruinose disk rests on a black 
hypothecium. Spores small, bilocular, 0,007-0,012™- long, and 0,005- 
0,007™"- wide. ——B. badia (Fr.) Koerb., must include, I think, an earth- 
lichen from the Yosemite valley, California (Mr. Bolander) which adds 
then another to the number of European species confined here to the 
west coast. Thallus of our plant made up of turgid or glebous, mostly 
irregular, and now somewhat stalked, brown squamules, with something 
of the make of those of the much nobler species next following. Apothecia 
(0,™™ 5-I1™™. wide) sessile, flat, opake, with a thin, at length scarcely 
flexuous margin, and a brown hypothecium. Spores small, 0,007-16™™. 
long, and 0,005-7™™. wide. The lichen is comparable also with the (exclu- 
sively lignicoline) B. turgescens (Nyl.) of New England, scarcely indeed 
differing at all in the spores; and B. turgescens, it is further observable, 
resembles still more closely Lecidea insularis, Nyl., which Flotow was 
inclined (Koerb. Syst. p. 239) — without, it is evident, microscopical inves- 
tigation — to regard as a variety of B. badia. ——B. pulchella (Schrad.) 
24 
