60 The Botanical Gazette. [February, 
semblance between the simplest form here described and Mr. 
Wolle’s description and figure’® of VW. pseudofurcata. The 
chief distinction given by him for this species is that it has 
‘‘only half as many lateral arms” as M. furcata. The origi- 
nal figure of M7. pseudofurcata Wolle, in the Bulletin of the 
Torrey Botanical Club is almost exactly like fig. 14, and prob- 
ably represents the same form. 
In this connection it is of interest to. note Wolle’s descrip- 
tion of M. furcata var. simplex.1® From this it will be seem 
that he collected and examined in Florida a series of forms 
showing all possible gradations from a form with two simple 
lateral arms on each side to one with but one simple lobe 
on each side of the semicell. He himself calls attention to 
the resemblance of the former to MZ. pseudofurcata Wolle, and 
says that it needs further examination. 
Combining these facts it seems to the writer that we afe 
lobed form. The varieties, decurta Turner, and simpler 
simple or bifid. 
No cause could be discovered for the greater variability 
the Long Island specimens unless it may be the lower tem 
perature of the water, the Connecticut specimens being from 
a shallow pool, where the water was quite warm. The lat 
ger size of the Long Island forms would perhaps indicate bee 
ter conditions for vigorous growth. 
Botanical Laboratory, Univ. of Michigan, Ann Ar bor 
EXPLANATION OF PLATE VI. 
: _ (Alf ) ig 2 
_Fig. 1. Portion of a filament of Micrasterias foliacea Botley. Kao - 
Single cell of same. x 400.—Fig. 3. Vertical view of frond, showiit 
of terminal lobe. X 400.—Fig. 4. Series of three cells, showing manuer” 
joining. X 400.—Fig. 5. Micrasterias pinnatifida (Kiitz.) Ralfs. x ie 
Fig. 6. Same, showing abnormal semicell.  400.—Fig. 7. Micraster ias f x 
cata Ag., typical form: Long Island. x 160,—Fig. 8. Same, Connecticut. 
Fig. 9-13. M. furcata Ag. showing variations. X 160,—Fig. 14 
form with lateral lobes all simple.  X 160. 
*S Bulletin of Torrey Botanical Club. 12: Z 88 
. 12: pl. sr. f. 6, 7. 1835. 
*6Freshwater algz of the United States > pl. 59. f, 6, 7. 1887. 
