
OF FILAMENTOUS, FRUTICULOSE, AND FOLIACEOUS LICHENS. 207 
from the density of the internal tissue and the thickness of the walls, this organ 
is easily enucleated by a needle. In age, also, the cavity becomes obliterated, 
and is occupied by a mass or kernel-like nucleus, usually more or less spherical, 
‘of a horny consistence, and sometimes slightly coloured. The spermatia are 
straight, linear, and very delicate, more frequently acicular, with pointed ends, 
than rod-shaped, with obtuse extremities. NyLANpER describes them as very 
slightly attenuated in the middle. This I have not specially noticed. Their 
length varies from sjoth to anath, the average being about z,:th ; seldom are they 
so small as ;nth to wmth long, as in some forms of P. Fahlunensis. Some- 
times, as in some forms of P. tiliacea, they are double the length when attached 
that they are when free. In this instance, while still attached to the sterig- 
mata, they measure gath to smth long, and when thrown off and free, sth to 
ath. In such cases it would appear probable that, after becoming free, the 
spermatia divide into two equal segments. The breadth of the spermatia gene- 
rally varies from x onth to smth, or it isinappreciable. The sterigmata are gene- 
rally longish, very narrow and delicate, consisting of 2-3, or 5-6 linear elongated 
cells, which are sometimes articulated, united, or superimposed at very irregular 
angles. Their length generally varies from ;th to jth, their breadth from ;;th 
to mmth. They are sometimes ;;th to sth long in P. tiliacea, in which species 
the sterigmata are among the longest and most handsome I have seen. In many 
species, associated with the ordinary spermatiferous sterigmata, occur numerous 
elongated, very ramose, sterile, delicate filaments, resembling those of Ramalina,— 
as in P. physodes, P. stygia, and P. sinuosa. In the latter species they are about 
sath long. These anastomosing filaments serve to fill up the cavity of the sper- 
mogone. Pycnides occasionally occur in Parmelia. It may be doubted by some 
whether they really belong to the species on which they occur. But their occur- 
rence among the undoubted spermogones of the species, all of whose external 
characters they possess, and the acknowledged existence of pycnides in other 
lichens, similar to those of many fungi, seem to me strong reasons for regarding 
them as really pertaining to the lichens, on whose thallus they are found. They 
are in all respects similar to spermogones, except in regard to their stylospores 
and sterigmata. I found them chiefly in two Irish specimens, P. saxaiilis from 
Connemara, and P. sinuwosa from Dunkerron. From their abundance and pro- 
minence, the genus Parmelia is a good one in which to study spermogones. 
Species 1. YP. caperata, Ach., 
Which occurs in Europe, Africa, America, Asia, and Australia. 
Specimen 1.—Great stones, near Penzance, Cornwall; in Herb. Hooker, 
Kew. The thallus is very large and handsome—nearly a foot in diameter. 
Where the cortical layer is intact, the surface of the thallus is very 
rugose and warted. But the thallus is nearly altogether devoid of a cortical 
