OF FILAMENTOUS, FRUTICULOSE, AND FOLIACEOUS LICHENS. 155 
spermogones—or brownish-red in species with scarlet apothecia—contrasts well 
with the pale straw-yellow or gray of the thallus, and renders them particularly 
conspicuous in this genus. The line of junction between the spermogone and the 
thallus is readily seen, and the sudden bulging of the barrel-shaped organ adds 
to this effect. The cavity of the spermogones is generally simple; but I have 
seen it sometimes sub-compound or divided into several obscure compartments 
or sinuses, as in C. macilenta. This cavity contains abundance of mucilage, in 
which are imbedded the spermatia. In species with scarlet apothecia, and 
occasionally also in those with brown fruit, as sometimes in C. pyxidata, this 
mucilage has a rose tint. The emission of the spermatia can readily be 
studied, by placing the spermogoniferous tips of the ramuscles of C. rangi- 
ferina or C. furcata in a drop of water between glass slides, and subjecting 
them to moderate pressure under the microscope. The genus Cladonia is, 
therefore, a good one in which to examine the spermogones and their contents. 
There is a remarkable uniformity throughout the whole of the species of Cladonia, 
in regard to the form and size of the spermatia and sterigmata. The former are, 
in all cases, curved when free, though they sometimes appear straight, or nearly 
so, while yet attached. They are somewhat crescent-shaped, that is, they are 
pointed or acute at the ends, and thicker in the centre. Their length varies from 
auth to ~anth, their breadth from ;;nth to sath. They are sometimes so short 
as amth to sath. They must not be looked for in old spermogones, with large 
gaping ostioles, from which they have long since escaped. While attached to their 
sterigmata, they are sometimes double the size they are when free, a phenomenon 
that is of frequent occurrence in lichens. The sterigmata are, in all cases, very 
delicate, linear, simple cells, very ramose at the base, varying in length from 
mth to znth, with a breadth of smth. With age they become elongated and 
sterile, filling the whole cavity of the spermogone, while, at the same time, they 
frequently acquire a brown tint. Occasionally, though rarely, elongated, hyper- 
trophied, sterile filaments project from among the ordinary spermatiferous ones, 
as in C. rangiferina in one or two instances. Spermogoniferous forms include 
many, at least, of the puzzling and anomalous varieties of species of Cladonia 
described by the older authors. 
SPECIES 1. C. pyxidata, Fr., 
A cosmopolite; occurring almost in every quarter of the globe hitherto explored. 
Specimen 1.—Old wall, Caerlaverock Road, Dumfries, August 1856, W. L. L. 
A deformed and degenerate form, with very large podetia, and scyphi covered 
with furfuraceous scales. The spermogones are roundish, brown, distinct tubercles, 
borne on small digitate prolongations from the margins of the scyphi, and having 
a perceptible ostiole. The interior contains a very beautiful and abundant lake- 
coloured mucilage. The spermatia are chiefly straight. 
