(162) 
locular spores in the black, convex form of B. atro-purpurea. In a lichen 
(B. fusca, Hepp) which is an exceedingly near relation (‘gehdrt jedenfalls 
in die ndchste Nahe, Koerb. l. inf. cit.) of the present, the author last 
named (Parerg. p. 143) describes however ‘ dusserst wandelbare (mono-, 
dy- bis tetrablastische) Sporen’; an observation not without special inter- 
est from the point of view of the present memoir. 
The group we have just considered exhibits the first modification of 
the originally simple, but finally plurilocular spore of Biatora, as here 
taken. It was not obscurely foreshadowed in the larger assemblage of 
species (with commonly simple spores) which preceded it, and it antici- 
pates in the same way, by sufficient indications, that now to come before 
us. Here the spore (‘anfinglich meist dyblastisch, Koerb. Syst. p. 211) 
assumes a dactyloid, or at length fusiform shape, and becomes regularly 
quadri-plurilocular ; the type and only distinction of the genus Bilimbia 
of authors. 
Biatora trachona, Flot. in Zw. exs. n. 117, occurs, and is probably com- 
mon, on shaded, granitic rocks, in Hampshire, Massachusetts; and the 
oblong or dactyloid, quadrilocular spores agree with those of my speci- 
men of the cited European lichen; to which Nylander also referred the 
American plant. In otherwise similar, Vermont specimens (Mr. Frost) 
the spores are mostly simple (only shewing at length irregular indications 
of division) and agree better with the description of Koerber (Syst. p. 
197) who has referred the species to the group with simple spores. — 
B. tricholoma, Mont. Guy. p. 35, appears to present no features of impor- 
tance to separate it from a Cuban lichen, growing upon leaves and bark 
(Mr. Wright) which I cannot distinguish from the later Lecidea leucoble- 
phara, Nyl. The latter was founded on specimens from the low country 
of South Carolina (Mr. Ravenel) and, according to Nylander (in Prodr. 
Fl. N. Gran. p. 52, not.) it has occurred also in the north of France. The 
minute apothecia are distinguishable by an accessory, white-fibrillose 
border, relieved by the dark-greenish crust. This accessory border be- 
coming obsolete, the proper margin is finally less obscure. Spores oblong 
and subfusiform, quadrilocular. ! B. artyta (Lecidea, Ach. L. U. p. 170) 
was from Schleicher, and Scherer pronounces the latter’s specimens of 
t, and Heterothecium leptocheilum, Tuckerm. (Obs. Lich. 1. c. 5, p. 280; Lich. Cub. 
n. 227). And there is not wanting other evidence looking towards a possible con- 
nection of the northern lichen with the microsporous section of Heterotheciwm. 
1 Other tropical species referable to the present group, and possibly occurring 
within our southern limits, are Biatora triseptata (Hepp) M. & V. d. B., found by 
Mr. Wright in Cuba, and a more remarkable form of which (f. artyloides, Tuck.) 
is given in Wright Lich. Cub. n. 207; B. leucocheila (Lecidea, Tuck. Obs. Lich. 1. 
c. 5, p. 278) also a Cuban lichen; as are B. pusilla, Mont., B. palmicola (Lecidea, 
Tuck. 1. c.) B. scitula (Lecidea, Tuck. 1. ¢.) B. pellea (Lecidea, Tuck. 1. c.) and 
B. thysanota (Lecid.1.¢.), Withthe last is in some respects comparable B. majorina 
(Lecidea, 1. c.) included in Lindig Herb. N. Gran., n. 811. 
