The Classification of Lichens. i'07 
Ramolodei, Phyllodei and Placodei, having lecanoroid or parme- 
lioid apothecia, the margins or rims being derived from the thallus. 
Lecideales include Crombie’s Cladodei, Gyrophorei and 
Lecideei, the apothecia being without thalline margins or algal 
cells. The family Coenogoniaceae is placed here, though the two 
British representatives, Ccenogonium ebeneum and Rucodimn rupestre 
are invariably sterile. 
The Graphidei (Graphidiales or Graphidinese) correspond to 
the same groups in Crombie’s synopsis, together with Dirina, 
Rocella and Lecanatis (five species of which were formerly included 
in Lecidea), the lirelline, rotundate, or irregular apothecia due to the 
probable Pharcidioid or Hysterioid ancestors of the fungal sym¬ 
biont, being the determining features. Agyrium is now relegated 
to the Fungi, Rehm considering it to be a member of the Bulga- 
riaceae. 1 
The Pyrenodei (Pyrenocarpineae) include Crombie’s series of 
Pyrenodei and Peridiodei with the exception of the genera Strigula 
and Endococcus which are now classed as fungi. The determining 
factor in this group is the Pyrenomycetioid ancestor of the fungal 
symbiont, the sporocarp being a perithecium usually opening by an 
apical ostiole. 
Myriangium, placed by Crombie in a distinct group, is now 
considered to be a fungus. In the monograph, Part II, the nature 
of the algal constituent is given, and, in some cases, the probable 
ancestry of the fungal constituent is referred to; but where the 
latter is indefinite, the somewhat speculative views of Schneider 2 
have been generally, and, perhaps wisely neglected, since the 
book does not pretend to be a text-book of lichenology, but an 
enumeration and description of British species. 
The different series are divided into orders, and these again 
into many genera, useful keys being provided in each case, so that 
it is a matter of little difficulty for a lichen-worker to run down a 
plant to its proper genus. 
The genus Lecidea is divided according to the form of the 
apothecium, number of spores in the ascus, and the colour and 
septation of the spores, into eleven genera, Gyalecta, Biatorella, 
Biatorina, Bilimbia, Bacidia, Buellia, Leciographa, Rhizocarpon, 
Bombyliospora, Lopadium and Lecidea, the last generic name 
being retained for some 200 species, having eight simple spores in 
the ascus. 
In the Graphidiales, there are six British sub-divisions or 
orders, three of which, Dirinaceae, Roccellaceas, and Lecanactaceae, 
were not placed by Crombie in his Graphidei. 
Lecanactacese contains the genera Lecanactis and Platygrapha, 
the former genus consisting of five species separated from Lecidea, 
on account of the algal symbionts (Trentepohlia) and the form of 
the apothecia. Arthoniaceas contains two genera, Arthonia and 
Arthothelium, the latter including two species with uniform spores, 
formerly placed under Arthonia by Leighton and Crombie. Chio- 
dectonaceae contains the genera Chiodecton, Glyphis, Enterographa 
and Sclerophyton, the last two being formerly placed in the genus 
1 Massee’s “ Fungus-Flora,” 1895. 
1 “ A Text-Book of General Lichenology,” 1897. 
