272 DR LAUDER LINDSAY ON THE SPERMOGONES AND PYCNIDES 
lobes, on their flat surface. They are conspicuous when moistened, amid the 
dark-ereen thallus. 
Specimen 2.—Malham, Yorkshire; Dr Carrinctron, 1857. The spermogones 
are brown disks or warts,—distinctly perforate or ostiolate on the apex,—scat- 
tered over the surface of the lobes among the apothecia, and resembling nascent 
apothecia. 
Specomen 3.—Var. furvum, Stroove Head, County Donegal: Prof. Dickie, 
1852. This is a form with a furvous or granulate thallus; it includes Collema 
rupestre, Scherer exs. 412, and is probably also what NyLANnpER describes as 
C. furvun. The spermogones are dotted about the margins of the lobes, on 
their flat surface. They are very minute, pale, brownish-yellow disks,—distinct 
when the thallus is moistened,—imbedded amid the dark-green tissue of the 
thallus. The spermatia are about jzaoth long, and »,qth broad, rod-shaped, 
seated on the apices and sides of long arthrosterigmata. 
Species 3. ©. furvum, Ach., 
Which occurs alike in Northern America and in Europe. This I regard simply as 
a variety of the preceding, characterised by the possession of a granulate and 
rough thallus. 
Specimen 1.—Scurer exs. 414 (sub Parmelia rupestris B. furca, c. fulr- 
ginea); on stones and the trunks of trees, Switzerland. The spermogones 
closely resemble those of Leptogium tremelloides. ‘They are round disks, of a 
yellowish or light-brown colour, with a deeper brown, central, punctiform ostiole. 
They are usually indistinct amid the deep-green thallus, unless when the thallus 
is moistened, and held up between the eye and the light. They are studded 
about the edges of the lobes, on their flat surface. 
Specimen 2.—Scu#RER exs. 499 (sub Parmelia nigrescens 8. conglomeratum) ; 
on the trunks of various trees in the milder parts of Switzerland,—in my copy 
(original ed. 1843). The spermogones are as described in No. 1; they are much 
less distinct than in Leptogium tremelloides, on account of the very dark-green 
colour of the thallus, and its furfuraceous surface. The spermatia are rod-shaped, 
about jpc0th long, on arthrosterigmata about®;;th to ath long. 
35,900 
Species 4. C. melenum, Ach., 
Also occurring, like the last, in Northern America and Europe, and including, as 
a variety, C. cristatwm, Scher. Among its synonyms are Collema marginalis, 
Hook. ; Parmelia multifida B. marginalis, Scheer. En. 255, exs. 420; Collema, — 
Korb. 409; Lichen jacobewfolius, Bernhardi; and Lichen marginalis, E. B. The 
spermogones are immersed and discoid, as in the species already described. 
They may sometimes be mistaken for, or confounded with, a small parasitic 
Spheria, whose perithecia are similarly immersed. It is possible that WALL- 

