480 SmitH: ALGAE FROM THE LAKES OF WISCONSIN 
Diameter of cell without processes 24-18 »; with processes 
(diagonally) 70-50 w; diameter of processes 12-9X8-5 x; length 
PLATE 26, FIGS. 19-20 
Distrigution: plankton, Cranberry, Lost, No Mans and Par- 
dee Lakes. 
This striking form is confined to the plankton of lakes in the 
northern part of the state. It resembles T. limneticum Borge toa 
certain extent but agrees more nearly with the description of 
T. gracile (Reinsch) Hansg. The processes differ from those of 
T. gracile, however, since when they are seen in a side view they 
are narrow but in a top view they are broad. The processes end 
in two horns in T. gracile while in this species there are often three. 
Tetraedron lobatum polyfurcatum var. nov. 
Cells four-sided, flat or pyramidal. Angles prolonged, taper- 
ing but slightly. Prolongations branching three to five times, 
ultimate branches with three spines. Prolongations nearly as 
long as cell. Sides of cell incurved. , 
Diameter (without processes) 20-15 »; (with processes) 40~- 
30 w; diagonal diameter 50-35 u. 
PLATE 26, FIGS. 21, 22 
DISTRIBUTION: plankton, Muskallonge and Pardee Lakes. 
This may be classed as a variety of T. lobatum on account of the 
cell-shape, but the extensive system of rebranching apical pro- 
longations is not found in any described variety of T. lobatum. 
The branches resemble 7. enorme (Ralfs) Hansg. but the sides 
of the alga under consideration are too deeply incised and the 
corners of the cells too long to regarditas a variety of T. enorme. 
Actinastrum gracillimum sp. nov. 
Colonies of four or eight cells radiating from a common center. 
Cells elongate, cylindrical or slightly tapering. Chromatophore 
single, parietal, without a pyrenoid. 
Cells 18-14 » long, 2~1.75 p» wide. 
PLATE 26, FIG. 23 
DistRIBUTION: plankton, Kegonsa and Mendota Lakes. 
This is much more delicate than any previously described 
species of Actinastrum. 
