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others from the same locality show them to be O. vulgatum. Prof. 
Underwood has collected at Baldwinsville, N. Y., a set of young spe- 
cimens of O. vulgatum, on June 14, 1890, part of which he 
pressed and the rest he cultivated in the laboratory until they ma- 
tured. The smallest ones, with the shortest petioles and pedicels, 
had the blade almost round, like those of Dr. Gray and Mrs. Mil- 
lington. He also has specimens from White Lake, Jamesville, 
New York, and West Goshen, Connecticut, which might well be 
taken for O. arenarium, but at the latter station he found all the 
intermediate forms which connect with O. valgatum. In fact, his 
herbarium is rich in uncommon and intergrading forms of this 
species. I have seen one set of small European specimens which 
are intermediate between O. vu/gatum and O. arenarium, and these 
were collected near Venice by Rigo, and have small ovate-lanceo- 
late blades, and none of them exceed 14 cm. in height. 
Mr. Willard N. Clute called my attention to the notes in the 
Linnaean Fern Bulletin, and told me that at the time that O. vulga- 
Zum was distributed to the members of the Fern Chapter, he had 
been struck by the great variation in the size of this fern. I wrote 
to Mr. Stewart H. Burnham, of Vaughns, N. Y., who kindly sent 
me a very interesting series of variations, the youngest of which, 
collected in May, 1896, are the exact counterpart of Dr. Gray’s 
small specimens from Exeter. He also collected on July 7th, in 
a limestone pasture, small double specimens very closely ap- 
proaching the Italian specimens collected by Rigo. Other speci- 
mens from the edge of the swamp and from beech woods are the 
large elliptical and oblanceolate forms of O. vulgatum. One of 
them is remarkable for the extreme elongation of the fertile Spike 
beyond the sporangia. 
One of the most marked characteristics of O. arenarium, aside 
from its habitat, is its habit of growing with usually two fronds 
from the same rootstock. This has also been observed in speci- 
mens of what appear to be O. vulgatum, though, in four out of 
seven cases noted, the blades of the sterile frond, whether bearing 
fertile spikes or not, are much reduced in size and venation, be- 
coming either short or oval, as in Chapman’s specimens from 
Florida, and Canby’s from Pennsylvania, or else bearing one nor- 
mal frond and another much narrower. Prof. Eaton, however, had 
