38 
PRErARATION OF GREEN ALGAi. 
It appears to be most convenient for the purpose to use 40°- 
50° Cels, during about two minutes. 
In the Spirogyra the chlorophyl bands, when the plant is 
boiled, also keep tolerably well. I therefore often have applied 
heat in preparing them. The different species seem to require 
different degrees of heat. 
ADDITIONAL BRITISH DESMIDS. 
By M. C. Cooke. 
Since the notice of “ British Desmids ” in our last, we have had 
the opportunity of consulting a collection of an extensive character, 
made over a period of many years, by Mr. A. W. Wills, of Wylde 
Green, and found amongst them the following species, which had 
only been previously recorded in Ireland : — 
Tetxachastrum mucronatum, Dixon. 
In all intermediate stages between the typical form and Tetra- 
chastrum oscitans, R. 
From N. Wales. 
Micrasterias angulosa, Hantsch. 
In Sutton Park, near Birmingham. 
Cosmarium pseudopyxamidatum, Lund. 
North Wales. 
Cosmarium speciosum, Lund, 
Dunkeld. 
Two or three other species of Cosmarium not yet determined. 
Staurastrum cerastes, Lund. 
Barmouth. 
Docidium nodosum, Bailey. 
Found at Barmouth, August, 1867. 
Closterium directum, Archer. 
Sutton Park, near Birmingham. 
Closterium Fritchardianum, ArcJcer. 
Barmouth, N. Wales. 
Closterium gracile, Breb. 
Barmouth, N. Wales. 
Closterium cynthia, De Not. 
Sutton Park, near Birmingham. 
Apparently this species, with a striated membrane, although not 
so robust as the figure by De Notaris. 
