
OF FILAMENTOUS, FRUTICULOSE, AND FOLIACEOUS LICHENS. 173 
of their gonidia. In Nephromium, according to NyLaNnpER, the gonidia, or rather 
bodies representing gonidia, upon which he bestows the name gonima, consist of 
granules without a cell-wall, and which are chiefly bluish; in Nephroma, on the 
other hand, true gonidia occur, which have a distinct cell-wall and contents. In 
a word, the one genus differs anatomically from the other, as Pannaria does 
from Psoroma. The separation seems to me a most unnatural and unnecessary one. 
Species 1. J. arcticum, Fr., 
A large handsome species, which inhabits the arctic and antarctic regions. Ny- 
LANDER describes it as possessing small rod-shaped spermatia, seated on arthro- 
sterigmata, as in Nephromium tomentosum. 
. GENUS III. Prtticera, Hofm. 
Spermogones containing true spermatia,—that is, spermatia having the usual 
characters,—do not occur in Pelizgera; but there are sometimes found marginal 
tubercles, resembling the spermogones of Nephromium, containing sporoid cor- 
puscles. The latter are regarded as spermatia by TuLAsNE; and as stylospores 
by NyLANDER, with whom I concur. It appears to me very desirable to draw a 
distinction between spermogones and pycnides in regard to the character of their 
corpuscles, and to call spermatia corpuscles of uniform size, and generally more 
or less linear form; and stylospores those which are variable in size, and generally 
more or less oval or pyriform. I have acted throughout the present monograph 
on this principle, in describing spermogones and pycnides respectively. This is 
a classification or nomenclature of convenience, and as yet provisional. It is quite 
unconnected with any view or theory as to the physiological functions of these 
corpuscles, and the organs which contain them. Viewing them by this light, then, 
the marginal tubercles of Saliigera are, in my opinion, Pycnides. There are not 
wanting, however, circumstances or analogies favourable to TuLASNr’s idea. He 
draws attention to the fact, that in Nephromium, bodies having the same site and 
same external aspect contain true spermatia seated on arthrosterigmata; he 
argues that the contained corpuscles in Peltigera merely differ in form; and he 
infers that in this genus, therefore, we must regard the conceptacles which contain 
these bodies as spermogones. The pycnides, then, of Peltigera are largish brown 
marginal tubercles, closely resembling the young apothecia, which are likewise 
marginal. They are so rare, however, that I have not once been fortunate enough 
to meet with them, and I therefore owe my descriptions to TuLasnn.* The dia- 
meter of the organ in P. polydactyla is from th to mth. The stylospores are 
_ generally oval or pyriform, varying in length from wath to zath, with a breadth 
_ usually of sath to mnth; they frequently contain distinct oil globules in their in- 
* Mém. Lich., p. 200, Plate IX. 
VOL. XXII. PART I. ya's 
