OF FILAMENTOUS, FRUTICULOSE, AND FOLIACEOUS LICHENS. 239 
articulations. In Physcia, the spermogones are more frequently papilleeform, or 
tuberculiform, than in Parmelia. Sometimes they are very large and prominent, 
particularly when they become confluent, and assume the form of irregular 
tubercles, as in P. ciliaris. The diameter of the spermogone in this species is 
sth; while in P. parietina it is about ten times less. The spermogones are largish, 
distinct, black cones in P. stellaris and other species with a grayish or whitish 
thallus. In other cases, they are brown. Sometimes they are covered with a 
white pruina, as in P. pulverulenta. In P. parietina, flavicans, chrysophthalma, 
jiammea, villosa, and other species, they are orange-coloured cones or warts, 
which become very conspicuous and beautiful where the plant has a grayish 
or whitish thallus, as in P. villosa. In this species, also, they may be so large 
as to be visible to the naked eye. The ostiole is usually very minute and 
round. Sometimes it becomes stellate-fissured with age, as in P. pulverulenta. 
Frequently, also, in the old state of the spermogone, it assumes the form of a large 
roundish perforation, with more or less distinct, turgid margins, as in P. aquila. 
If the body of the spermogone fall out in age, as is occasionally the case, the 
ostiole may expand still more, and become saucer-shaped, or like cyphellee, as in 
the same species. The diameter of the simple, round, imperceptible ostiole is fre- 
quently about th to ath, as inP. pariectina. The spermogonal envelope is formed 
of roundish or cubical cellules, more frequently brown than any other colour. The 
cavity of the spermogone is generally simple; but in several species, and particu- 
larly in the case of compound or confluent spermogones, it is divided into sinuosi- 
ties or compartments, as in P. ciliaris and P. villosa. The spermatia are gene- 
rally shorter than those of Parmelia; they are usually rod-shaped or acicular, 
sometimes sub-ellipsoid. They vary in length from gqth to smth, a large 
number being from gath to sthlong. Their average breadth is smth to santh. 
The sterigmata seldom consist of only two or three articulations, as in Parmedia, 
nor are these articulations often long linear cells. They are more usually longish, 
- ramose or simple, composed of more than five or six short, roundish or cubical 
cellules. These cellules have originally thin walls, which, however, become 
thickened by deposits in their interior. The arthro-sterigmata of Physcia, there- 
fore, somewhat resemble those of Sticta and Collema. Their length varies from 
goth to zath generally. 
Sprcius 1. P. ciliaris, DC., 
A native of Europe, Africa, and North America. This species is of much historical 
importance and interest to the lichenologist, inasmuch as in it spermogones were 
first discovered and described by Irzicsonn, in Germany. It is, moreover, a 
_ common lichen, and a species abounding in large, well-marked spermogones, 
visible usually to the naked eye. They are obtuse, very prominent warts or 
tubercles, scattered on the convexities of the lacinixe; they are isolated or con- 
