LICHENS. 
59 
In a great number of species the author has met with, on the same 
specimen, some of the apothecia adhering and forming a pseudo- 
stroma, or, more or less, clustered, whereas others were completely 
free and isolated. With regard to such species it is stated that 
some have been placed in genera characterized by a pseudostroma, 
others in genera distinguished by isolated apothecia even by the 
same author. 
Such intermediate forms are very numerous, as in Graphis , 
Glyphis , etc. In the genus Pertusaria transitions between simple 
and compound apothecia occur ; on the other hand, confluent 
apothecia are shown to occur in genera Lecidea , Lecanora , and 
Buellia. 
In the last named the transition is so evident that no author 
would suggest a division of these genera on the basis of simple and 
grouped apothecia. 
Groups characterized by the paraphyses. — Many natural genera 
are met with in the Pyrenolichens and the Graphideae that are dis- 
tinguished from each other by characters afforded by the paraphyses 
in conjunction with those afforded by the spores. Branched and 
connected paraphyses occur in the following genera of the Pyreno- 
lichens : — A spidopy renium, Heufleria, Astrothelium , Campylothe- 
lium , Pseudopyrenula, Leptor aphis, Microthelia, Arthopyrenia, 
Haploprenula. On the contrary the paraphyses are simple or not 
connected in Aspidothelium, Pornia, and Strigula , and variable in 
Bottaria, Pyrenula , and Thelenella . Among the Graphidese they 
are branched and connected in Opegrapha , Helminthocarpon, 
Chiodecton , and Arthonia , simple or not connected in Acantothecium , 
Graphis , and Melaspilea. In the Pertusariese they are also 
branched and connected. In the higher groups the paraphyses 
are, in general, simple or variable, and in the latter case are alto- 
gether insufficient for characterizing even the minor groups. 
Especially in the genus Parmelia it may be seen that amongst 
allied species some have the paraphyses simple or free from each 
other, whereas in others they are connected or anastomose. In 
Lecidea versicolor (Fee), L. micrococca (Koerb.), Myl., etc., the 
paraphyses are branched and connected, whereas in most of the 
members belonging to the same groups as the above they are 
simple. Again, in Lecanora symmictella (Wainio), belonging to 
the pulecanora (Th. Fr.), also some belonging to the sub-genera 
Lecania (Mass.), Wainio, and the species belonging to Calenia 
(Miill. Arg.), the paraphyses are branched and connected, whereas 
in the remainder of the species of Lecanora they are simple. As 
most of the species enumerated are closely allied to species with 
simple paraphyses, this character would not appear to be sufficient 
for groups in these genera. 
The genus Ochrolechia is characterized, in addition to the 
spores, by branched paraphyses that are not connected. 
Chemical characters. — Although many authors protest strongly 
against the value of chemical diagnoses for the determination and 
classification of Lichens, nevertheless these very frequently coincide 
