( 209 ) 
spores, as described by Fée Suppl. p. 29) for I have scarcely seen good 
ones, are eruceeform, 10-12-locular, and colourless. 
Of the second division (stock of G. dendritica) five species have been 
detected within our limits. —— G. dendritica, Ach., occurs rather sparingly 
on the coasts of New England, and in New Jersey (Mr. Austin) but becomes 
very common and much varied at the South (South Carolina, Mr. Ravenel ; 
Florida and Alabama, Mr. Beaumont; Louisiana, Hale; Texas, Mr. 
Ravenel). The thin, dark-brown hypothecium sometimes blackens.—But 
again, the hypothecium becomes pale, or even colourless (G. imusta, Ach., 
Nyl., founded on a Canadian lichen; G. Smithii, Leight.) this state exhib- 
iting all the modifications of the species, and being otherwise undistin- 
guishable. It occurs throughout the same region with the other. —The 
apothecia of G. dendritica, in both conditions of the hypothecium, become 
finally often confluent, forming rounded or irregular, variously divided 
patches (Medusule sp., Auctt.) which constitute the v. medusula, Nyl. ; 
occurring commonly at the South, and found at New Bedford, Mass., 
(Mr. Willey). Spores of G. dendritica in eights; broad-oblong; com- 
monly four- but reaching six-to eight-locular; the length twice and a 
half to four times exceeding the diameter; fuscescent. The spores are 
scarcely eruceform, being less elongated than in most of my specimens 
of the European, and of the tropical lichen, though more like those of 
such states as Rabenh. Lich. Hur. n. 606. The southern plant is also 
curiously marked by the irregular division (of sometimes all, but more 
commonly part) of the spore-cells into two; an anticipation at least of 
the muriform stage. —— G. scalpturata, Ach., inhabiting tropical America, 
is a rather larger, finer lichen than the last, but closely akin to it. It has 
occurred here in Louisiana (Herb. Austin). Spores, so far as observed, 
solitary, muriform-multilocular, brown, reaching at length 0™™-,083 in 
length by 0™™-,019 in width. But spores occur of half these dimensions; 
and the lichen is otherwise strictly comparable with one from southern 
Alabama (Mr. Beaumont) the brown, muriform spores of which measure 
0™™..041-69 in length by 0™™.,017-23 in width, and occur in twos, threes, 
fives, and eights, in the thekes. The young spores, in both these lichens, 
resemble those of the last species. The material in hand appeared to be 
sufficient, in the case of G. scripta, to fully authorize an expression of the 
opinion that the conditions of that lichen with muriform spores are not 
properly separable in species from the remainder, with which, in other 
respects, they undoubtedly agree ; and the argument could not but have 
its bearing on the strictly analogous case of G. elegans. It does not fol- 
low indeed that G. dendritica can be shown to be another example of the 
same sort; but there is at least no doubt of the very close relationship of 
G. scalpturata to the former (in its forms with colourless hypothecium) 
and such specimens of the latter as Lindig Herb. N. Gran. n. 750, as 
compared with n. 729, and Lindig, 2, n. 139, as compared with n. 2637, 
reduce perhaps the question of a specific distinction between the two 
27 
