ie, 
266 DR LAUDER LINDSAY ON THE SPERMOGONES AND PYCNIDES 
rocks among the Alps. The spermogones are largish tubercles, seated at the 
corners of the squamules, and about the periphery of the thallus, sometimes also 
scattered among the apothecia. They are usually flattened on the top, are of a 
paler or lighter colour than the thallus, and have orange-red ostioles. The 
spermatia and sterigmata are those of the preceding species. 
Species 8. P. scorigenum, Mont. (sub Lvernia). 
Specimen 1.—Canary Islands, Dr Leman; in Herb. Hooker, Kew. The spermo- 
gones are seated on the convexities of the lacinice as orange papillee or tubercles, 
which are much lighter in colour than the disks of the apothecia. The sper- 
matia are rod-shaped, and about anth long; the arthrosterigmata are those of the 
two preceding species. This plant comes very close to Physcia villosa, both in regard 
to its spermogones and apothecia ; so close, indeed, that, were a trivial difference 
in the character of the thallus overlooked, it might almost be included. 
Sprecigs 9. P. elegans, DC., 
One of the most widely-spread species of Placodiwm, occurring in Europe, America, . 
Asia, and Abyssinia. It is also one of the most beautiful species. 
Specimen 1.—Var. miniatum, Scu#RER exs. 338 (sub Parmelia elegans a. 
miniata); on sunny stones among the Alps. The spermogones resemble in site 
‘and external appearance, as well as internal structure, those of the following 
species. They are small orange-red tubercles, scattered about the ends of the 
lacinize. The spermatia are sub-ellipsoid or rod-shaped, atomic as to size, seated 
on very indistinct arthrosterigmata. 
Species 10. P. murorum, DC., 
A cosmopolite, familiar and beautiful species. Its spermogones, in regard to site, 
outward appearance, and internal structure, closely resemble those of Physcia 
parietina. They are small papillee or warts, scattered about the periphery of the 
thallus, isolated or grouped two or three together. Their colour is somewhat 
deeper than that of the thallus. They sometimes resemble nascent apothecia. 
The ostiole is usually minute, round, and imperceptible; occasionally it has a 
thick margin, and sometimes it is fissured. The greatest diameter of the spermo- 
gone is ath. The internal tissue is hard, dense, whitish, opaline. The form of 
the body of the spermogone is oblong and irregular; the cavity is divided into 
many sinuosities. The gonidic layer of the thallus sometimes girds the immersed 
body of the spermogone, which is more usually directly plunged in the white medul- 
lary thalline tissue. The sterigmata are ramose, and are composed of almost 
solid, cubical cellules. The spermatia are rod-shaped, and vary in length from 
smth £0 ipombl. | 
Specimen 1.—LEIGHTON exs. 113 (sub Parmelia); on mortar, ruins of Tong 

