Smith—Phytoplankton of the Muskoka Region. 345 
parallel. Length of polar lobe nearly twice the greatest breadth 
of lateral lobes. Polar lobe narrower, with parallel sides. 
Length 135-165 /x; breadth 130-150 /x; breadth basal portion po¬ 
lar lobe 15-20 /x; greatest breadth lateral processes 13-15 /x; 
breadth isthmus 15 /x. 
Butterfly (rrr), Burned Rock (rrr), Gull (1), (c), Muldrew (r), Pine 
(rrr), Silver (1) (s). 
This variety is remarkably constant in character, and all indi¬ 
viduals noted had but the single subdivision of the lateral lobe. 
It is much more delicate than the variety simplex , the margin of 
the lateral lobes never showing the marked convexity found in 
that variety. The polar lobe is also much more prominent and 
narrower than in the typical form. 
Micrasterias Mahabuleshwarensis forma dichotoma forma nova. 
PL IX, figs. 12-14; PL X, fig. 1. 
Differing from the typical form in the development of rudi¬ 
mentary accessory processes on the inner side of the incision of 
the lateral lobes. 
Length 150-165 /x; breadth 150-160 /x; breadth polar lobe 20-25 
/x; breadth isthmus 20-31 /x. 
Black (1) (rrr). Brush (rrr), Nelson (rrr), Nine Mile (rrr), White 
(r). 
The secondary lobelets on the lateral lobes of this form are 
quite irregular and are not normally found on all eight lateral 
branches of a cell but only on some of them. They may be re¬ 
duced to a small mammillate spine, but are always present in 
one form or another. This form possesses a great resemblance to 
M. americana (Ehr.) Ralfs, but is placed with M. Mahabulesh¬ 
warensis because both sides of the lateral lobes are denticulate and 
the polar lobe has the shape of M. Mahabuleshwarensis with long 
apical processes. 
Micrasterias foliacea Bailey 
Gull (1) (rrr), Rowley (rrr). 
COSMARIUM Corda 1834 
Cosmarium contractum var. papillatum forma minor forma nova. 
PL X, figs. 2-5. 
Length 30-32.5 n; breadth (without papillae) 23-25 /x; papillae 
1.25 /x long; breadth isthmus 6.25-7.5 y; thickness 15-17.5 /x. 
Thompson (aa). 
