Smith—Algae Found in Wisconsin Lakes 
639 
Genus CEIICIGENIA Morren 1830. 
Crucigenia rectangularis (Nageli) Gay. 
Eecherches sur le dev. et la class, de quelques algues vertes 100. pi. 15, /. 
151. 1891. 
II. Mill (rrr), Paddock (rr). 
III. Beaverdam (rr), Lac Court Oreilles (rrr). 
Crucigenia irregularis Wille. 
Biol. Cent. 18: 302. 1898; Nyt. Mag. f. Naturvidensk 38: 10, pi. 1, /. 15. 
1900; W. & G. S. West, Trans. & Proc. Bot. Soc. Edinburg 23 29, pi. 1, 
figs. 6-7. 1905. 
The cells of some of the smaller colonies from the plankton 
of Browns Lake were regularly arranged in the coenobe. This 
suggests a very large variety of C. rectangularis (Nageli) Gay 
but I consider them colonies of C. irregularis. In addi¬ 
tion to differences in cellular arrangement, the two species differ 
considerably in size so that the two need not be confused even 
though the cells are at times regularly arranged. Although 
most investigators state that pyrenoids are not found in the 
chloroplasts of C. irregularis, I have generally found them pres¬ 
ent. (Plate 11, figs. 2-3). 
II. Browns (rr), Camp (rr). 
III. Keserve (rrr). 
Crucigenia lauterbornei Schmidle. 
Allg. Bot. Zeits. 6: 234. 1900; Chodat, Mater, p. 1. fl. crypt. Suisse 1^: 206. 
fig. 127. 1902. 
Cells 4. 5-9 /A, wide, 8-15 p. long. Coenobes 15-25 p in diam. 
Multiple coenobia up to 150 p in diam. 
In the formation of the young coenobia, there is a rupture 
of the cell wall into two and not four parts as is generally stated. 
The gelatinous sheath enclosing the colony is very delicate and 
easily overlooked. The statement is generally made that the 
coenobes are held together by the gelatinous sheath of the colony. 
This sheath may play a part in holding the cells of the colony 
together, but the remnants of the old mother cell wall are also 
important and play the same role as in BictyospJiaerium, 
Westella and I)imorphococcus. (Plate 12, fig. 1). 
III. Chetek (rrr), Pokegeraa (rr), Prairie (rr), Eice (rr). 
