ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
81 
gonidema, the rows of cells which constitute it radiating and branching 
from a centre and forming a disc. By this character Arthoniopsis is 
separated from Arthonia, Chroodiscus from Ocellularia, Hotula from 
Platygrapha and Opegrapha, Opegraphella from Opegrapha, and Phyllo- 
porina from Porina. 
Rev. F. R. M. Wilson * describes a number of lichens collected in 
the colony of Victoria, including a large number of new species belong- 
ing to a great variety of genera, and one new genus Neophyllis, belonging 
to the Bieomycei, of which, however, no generic diagnosis is given. 
Anew species of Myriangium is described, M. dolichosporum, growing 
on the leaves of Hymenanthera Banksii. 
Structure of Cladonia,f — Herr G. Krabbe has undertaken a careful 
examination of the structure of this genus of Lichens, for the purpose of 
clearing up some doubtful points in its morphology. Of the three parts 
of which the lichen is composed, the protothallus, the “ podotia,” and the 
apotheces and “ spermogones," he shows that the “ podetia ” are not a 
part of the thallus, but of the organs of fructification ; their morphology 
is described in detail. 
The thallus consists of the three zones, the medullary, the gonidial, 
and the cortical layers, of which the last is continually dying off from 
above, and renewing itself by the growth of fresh filaments from the 
gonidial layer ; during this process algal cells are carried into the 
cortical layer, where however they perish, in consequence of the cortex 
being closed on all sides against the atmosphere. The thallus appears 
always to be developed out of soredes. It is in a definite zone of the 
gonidial layer that the ascogenous liyphae are formed, arising usually from 
sterile filaments, and becoming gradually differentiated in the course of 
their growth. Their number in a fructification varies greatly, but they 
are always alike. They usually break through the cortical layer in the 
form of a small tuft. The “ podetia ” become hollow, and the ascogenous 
hyphae are ultimately ruptured from the place of their formation, and 
grow into the hymenium, which is formed at the apex of the fructifica- 
tion out of vegetative filaments; they develops at their apices into sacs. 
Various modifications of the mode of formation of the fructification in 
the different species of Cladouia are described, and the following classi- 
fication proposed : — 
I. Species with homosporous fructification and simple “ podetia ” ; no 
formation of funnels ; branching very slight, differentiation early (G. 
cmpiticia , cariosa, bacillaris, &c.). 
II. Fructification simple, or more or less branched; heterosporous 
(G. endivieefolia, squamala, &c.). 
III. Fructification much branched ; either heterosporous or homo- 
sporous ; differentiation late (G pyxidata, rangiferina, Ac.). 
Besides the ascogenons fructifications, Cladonia produces also 
conidial fructification (“ spermogones ”). They are formed in the thallus, 
and develope, by long-continued apical growth of the hyping, to fructi- 
fications closely resembling the ascogenous, the development of the 
* Journ. Linn. Soc. (Bot.), xxviii. (189L) pp. 353-74 (1 pi.). 
t ‘ Entwickelungsgesch. u. Morph, d. Cladonia,’ 4to, viii. and 160 pp. and 12 pis. 
Leipzig, 1891. See Bot. Centrnlbl., xlvii. (1891) p. 302. 
1892. 
G 
