48 AMERICAN FERN JOURNAL 
fronds of the two were alike. The fronds averaged 12 
to 15 centimeters in length and one centimeter in 
width. The stipes were about six centimeters long, 
slender and channeled. The average width of frond 
was one centimeter. The pinnae were nearly semi- 
circular or broadly semi-elliptic in outline, 5-7 milli- 
meters in width, 3-5 in length, coriaceous, dark green 
in color and bluntly and somewhat irregularly toothed; 
the shorter with a mid-vein which arose near the lower 
edge of the pinna, ascended nearly parallel to the rachis 
and gave off about four simple or forked veinlets on 
the outer side only; the more elongate pinnae with a 
more or less well-developed mid-vein with branches on 
‘both sides, as in typical plants of P. vulgare. 
Since it is often desirable to have names for such 
peculiar forms, this one may be called Polypodium 
vulgare, forma rotundatum pn. f.1 
BENNINGTON, Vr. 
Salvinia in Minnesota. 
F. K. BUTTERS. 
For some years the various floras of the eastern United 
States have reported Salvinia natans (L.) All. as occur- 
ring in the vicinity of Minneapolis. These reports 
seem to be based on material distributed by the Her- 
barium of the University of Minnesota about thirty 
years ago. In’ 1916, after a careful investigation of 
the origin of this material, Professor Rosendahl and I 
published the following statement: 
An analogous variation is found in the lant known as Nephrolepis 
Duffii Moore. This is a form of N. cordifolia in which the usually oblong 
pinnae are reduced to short, semi-circular exactly as in Mr. Rid- 
lon’s plant. Like it, too, N. Duffii is not a form developed under culti- 
vation, but was first found in the wild.—c. 4. w. 
