332 
NOTES ON THE BLUE-GREEN ALG&, 
WITH A KEY TO THE SPECIES OF OSCILLA- 
TORIA AND PHORMIDIUM. 
HAROLD WAGER, F.R.S, 
(Continued from page 308). 
A large number of species are not considered here, either 
owing to the uncertainty of their diagnosis or because of their 
rarity. Lists will be found in Gomont and De Toni. I have 
only included the better-known species, such as are likely to 
be met with, but I have included all that are described as good 
species by Gomont and Tilden 
At the end of the description of every species will be found 
references to Gomont, ‘G,’ and to Tilden, ‘T,’ giving the 
page, number of plate, and references to the figures given by 
each of these authors for the species. Thus, G. 218, 6, 22-23, 
means Gomont’s Monograph, page 218, Plate 6, Figs. 22-23, 
and the same order is used for the references to Tilden’s 
monograph. 
The key is only useful for purposes of a preliminary diag- 
nosis. In the final determination of the species reference must 
be made to one of the monographs on the group. For the 
convenience of students keys to the orders and families of 
the Blue-green Algze, and to the chief genera of the family 
Oscillatoriaceze. are also given. 
KEY TO ORDERS AND FAMILIES OF THE BLUE-GREEN 
ALG. 
1. Filamentous, multicellular plants; reproduction by 
hormogones; trichomes in a sheath or free 
Order I., Hormogoneze 2 
1. Unicellular plants, sometimes in colonies in a gelatinous 
mass; reproduction by spores or simple division 
Order II., Coccogonez 7 
Order I., HoRMOGONE&. 
2. Trichomes equal in diameter throughout or attenuate 
at apex, sometimes torulose, Sub-Order I., Psilonematez 3 
2. Trichomes strongly tapering, either from the base 
or from the middle towards both ends to form 
hair-like prolongations Sub-Order II., Tricohphoree 6 
Sub-Order I., PSILONEMATE2. 
Heterocysts present; sheaths present a od oe mth. i! 
Heterocysts absent; sheaths present or not 
Fam. IV., Oscillatoriaceze 
4. Trichomes of one or more rows of cells; filaments 
branched ; sheaths thick and firm, Fam. I., Stigonemacez 
4. Filaments with false branching or none; trichomes 
of a single row of cells se = oe af Ar 5 
Naturalist, 
Oo Os 
