117 
from the family {Anhistrodesnms^ Fediastrum and '’Sce- 
nedesmus)^ others can be united or divided. E. gr., 
Cylindrocystis Menegh., only a section in Br. Desm., 
is now generally recognised as a proper genus. As 
Micrasterias radiata Hass, and Closterium Ensis Focke 
have been neglected by nearly .all authors, they 
may rest so. But as Fenium closterioides Ralfs is a 
Closterium^ according to Lütke millier, its older name 
dost. Libelhda Focke has a claim of priority; its 
first name under dost, after 1848 is dost. {Netrium) 
Fenium Reinsch 1867. Didymoprium Grevillii Kütz. 
is more recent than Desmidium cylindricum Grev. 
(J)idym. cyl. Ralfs 1845), which is more commonly 
used, especially in later times, and ought to be re¬ 
tained. 
I propose the following rules for the nomencla¬ 
ture of the Desmidiaceæ. 
1. The nomenclature begins with The British 
Desmidieæ by Ralfs 1848. 
2. The authors of names, given earlier, but 
accepted by Ralfs in Brit. Desm., must always be 
quoted as such (e. g. — Ehrenb. sec. Ralfs in Brit. 
Desm.), except if the identification of the name in 
Ralfs’ Brit. Desm. and in the works of the older 
authors be very doubtful. 
3. Exceptions. The following earlier specific names 
have priority and must be retained: Closterium Lihel- 
lula Focke (if removed from Fenium) and Desmidium 
cylindricum Grev. {Didymoprium cyl. Ralfs 1845). 
The rule 3. is naturally not quite necessary. 
For several other sections of algae there are 
also standard works, from which their nomenclature 
can begin. I will here mention 3 such works, al¬ 
though the selection of names in the two last-men- 
