NEW SPECIES OF GREEN ALGAE 
297 
southeast of Lerna, Illinois. It fruits during May. Type in herb. 
E. N. T. Collections No. 1377, 1374, and 1842. Plate XXVIII, 
figures 1-3. 
MOUGEOTIA TUMIDULA nov. Sp. 
Cellulis vegetativis 6-8.5 M latis, io-20-plo longioribus; zygosporis 
inter 4 cellulas sitis, tumidis quadrangularibus 22-26 ii X 26-30 /jl, 
a latere visis ellipticis, angulis retusis, mesosporio hyalino evidenter 
subtiliter scrobiculato. 
Vegetative cells 6-8.5 M X 70-120 /x, zygospores adjoined by four 
cells; quadrate, somewhat tumid, 22-26^1 X 26-30 /x, eUiptical when 
seen from the side, angles retuse, median spore wall distinctly but 
minutely scrobiculate. 
This species resembles in size and retuse corners of the zygospore 
Mougeotia viridis (Kuetz.) Wittr. but differs in having the spore walls 
convex instead of concave, scrobiculate instead of smooth. It differs 
from M. gracillima (Hass.) Wittr. in its larger size, retuse angled spores, 
and the convex spore walls. Type in herb. E. N. T. Collection No. 
744. Found thus far only in the Embarras river, Wheeler, Illinois, 
Sept. 191 1. Plate XXVIII, figure 4. (Scale of figure i cm. = 25 ^i.) 
Oedogonium pratense nov. sp. 
Oedogonium dioicum, macrandrium, oogoniis singulis, rarissime 
binis, subdepresso-globosis vel late pyriformi-globosis, opercula apertis, 
circumscissione mediana, angusta sed distincta; oosporis depresso- 
globosis vel subglobosis, partem oogoniorum inflatum complentibus, 
membrana laevi; plantis masculis paulo gracilioribus quam femineis; 
antheridiis 1-2-cellularibus, saepe cum cellulis vegetativis alternis; 
spermatozoidis singulis; cellula fili basali forma, ut vulgo elongata; 
crassit. cell, veget. plant, fern 10-17 altit. 35-95 m; 
crassit. cell, veget. plant, masc 8-15 ix, altit. 30-70 /x; 
crassit. oogon 33-40 /x, altit. 33-50 
crassit. oospor 32-38 n, altit. 28-35 Ml 
crassit. cell, antherid 10-14^1, altit. 13-18 /x. 
Dioecious, macrandrous, oogonia single, very rarely two, sub- 
depressed globose or broadl}/ pyriform-globose, opercula te, division 
median, narrow but distinct; oospore depressed globose or subglobose. 
fiUing or nearly filling the inflated portion of the oogonium, membrane 
smooth; male plants more slender than the female; antheridia 1-2- 
celled, usually alternating with vegetative cells; sperms single; basal 
cell of filament commonly elongated ; 
