292 EDGAR NELSON TRANSEAU 
Spirogyra pratensis nov. sp. 
Caespites flavo-virides efformans; cellulis vegetativis 17-20 /x latis, 
4-12-plo longioribus; chromatophoris singulis vel binis, anfractibus 
1-8; generatio zygosporis vel aplanosporis ortis (conjugatio lateralis 
vel scalaris); cellulis fructiferis inflatis, ad 55 fx latis; cellulis sterilis 
turn cylindraceis turn inflatis vel buUatis (ad 90 ju latis) ; sporis 
ovoideis, ellipticis vel cylindraceo-ellipticis, 24-36 latis, 50-70 ju 
longis, maturitate flavescentibus. 
Forming yellowish green masses; vegetative cells 17-20 ju in diam- 
eter, 80-240 jj, in length, chromatophores one or two in a cell, making 
from 1-8 turns; reproduction by zygospores and aplanospores, conjuga- 
tion lateral and scalariform; fertile cells inflated, up to 55; sterile cells 
cylindrical, inflated, or bullate (diam. up to go fx); spores ovoid, 
elliptical, or cylindrical with rounded ends, 24-36 fj, X 50-70 fx, yellow 
at maturity. 
This species combines most of the characteristics of S. mirabilis 
(Hass.) Kuetz. and S. polymorpha Kirchner. From the former it 
differs in its dimensions (almost all living cells measure exactly 20 fx 
regardless of the habitat), in the constant occurrence of cells in the 
filaments with two chromatophores, in its regular production of zygo- 
spores, and in the tendency of the sterile cells to be inflated. S. 
mirabilis has been collected in this territory and like the European 
specimens varies considerably in dimensions, the cell diameter up to 
27, and it showed no cells with two chromatophores, and lacked the 
inflated sterile cells. From S. polymorpha this species differs in its 
dimensions, in its regular production of aplanospores, and in the 
presence of inflated sterile cells. As shown in the figures some of the 
fertile cells containing aplanospores have developed protuberances 
as in conjugation, but apparently without reference to adjoining 
filaments, as they show a definite tendency to alternate in successive 
cells. Another interesting feature is the occasional occurrence of 
cells containing aplanospores which have become attached to sterile 
cells, but the terminal wall of the protuberance has not been dissolved. 
This species is probably common in Illinois. I have recorded it from 
all the larger ponds, and Campus creek at Charleston; also from the 
Brookhart farm pond southwest of Oilfield. Type in herb. E. N. T. 
Collections No. 1103, 1822. Plate XXV, figures 12-14; Plate XXVI, 
figures 1-2. 
Spirogyra catenaeformis (Hass.) Kuetz. var. parvula nov. var. 
Filamentis plerumque sparsis; cellulis vegetativis 20-24 /x latis, 
2-5-plo longioribus; chromatophoro uno, anfractibus 1-6; cellulis 
