Notes on Recent Literature 
166 
considerably modified, though, owing to the necessity of keeping up 
some show of uniformity, the modifications have probably been 
fewer than they otherwise would have been. 
The students of lichens during the last twenty years have not 
been numerous, but tbe work of Zahlbrucher, Boistel, Jatta, 
Schneider, Bruce Pink, Hue, Miss Smith and others has placed 
lichenology on a different footing, and rendered some changes 
in classification and nomenclature absolutely necessary. When 
Nylander, Fries, Lindsay, Leighton, Mudd and Crombie described, 
figured, named and classified lichens, the real nature of these 
curious plants was unknown or a question of great controversy, 
but to-day few workers doubt that the structure of these plants 
is due to mutualism. 
In classifying them some difficulty is experienced in deciding 
on what symbiont the system should be based, whether the fungal 
or the algal constituent should be the determining factor to the 
systematise 
In all groups of plants the organs of reproduction are held to 
be of higher systematic value than the vegetative portions, and as 
the spore-bearing organs (asci)are those of the fungal symbiont the 
main lines of classification are generally determined by the fungal 
component of the plant. 
The old methods of classification into gelatinous, fruticose, 
foliaceous, and crustaceous lichens 1 has had to be practically 
rejected. 
A system of classification should take into account not only 
the present structure of the plants involved, but also their evolu¬ 
tionary history, interpreting the former in terms of the latter. 
This is a complicated business in a composite group such as the 
lichens, for even if the ancestors of the symbionts have not been 
eliminated, the modifications induced by their mutualism may have 
been so great that it is now almost impossible to trace them. 
The Basidiolichenes, in which the fungal ancestors belong to 
the Basidiomycetes, are not represented in this country, all the 
species included in this monograph belonging to the Ascolichenes, 
with apothecia or perithecia similar to those found in the 
Ascomycetes. 
The system adopted by Crombie in the first part of this mono¬ 
graph is apparently not followed by Miss Smith, judging by the 
modifications introduced into the second part, and the arrangement 
of specimens in the lichen cabinet of the Natural History Museum. 
Ephebacei and Collemacei of Crombie’s system, as well as all 
the other lichens (Stictinei, Peltigerei and Pannariei) having a 
more or less gelatinous thalius and blue-green algal cells are 
placed under Cyanophila, the algal constituent having the pre¬ 
ferential treatment as a systematic base. Pyrenidium, because of 
its perithecial method of reproduction, is now transferred to 
Pyrenocarpei. 
The modern group of Coniocarpi or Coniocarpinere corresponds 
to Crombie’s series Epiconoidei, in which, at maturity, the spores 
form a powdery mass on the surface of the apothecium. 
Parmeliales include most of the genera placed in Crombie’s 
1 See Vines’ “ Student’s Text Book of Botany,” 1896. 
