551 
elongated elliptical or oblanceolate forms the long narrow central 
areolae without any free veinlets, are more numerous. The im- 
mature and smallest fronds are more fleshy and the venation less — 
distinct, the areolae much smaller, with seldom any free veinlets. 
In some fronds there is rarely a distinct or continuous midvein, 
somewhat stronger than those on either side, but in most fronds 
the central part of the leaf is marked by the extremely elongated 
and approximate narrow areolae. | 
In size Prof. Eaton says they vary “ from two to twelve inches.” 
Two inches would only include such very young forms as those 
collected by Dr. Curtiss at Exeter and Blytt’s from Christiania. 
The usual size varies from 6-16 inches and the relative length of 
‘the stalk above and below the leaf also varies, the younger ones 
being longer below; for, as the plant matures, the fertile spike 
elongates and often exceeds the common petiole below the leaf. 
In O. arenarium it is 2-3 times longer, the petiole being quite 
short and immersed; this is true also of the small European speci- 
mens in the Gray Herbarium collected near Venice by Rigo, and 
of Macoun’s multiple specimens from Hastings. 
Prantl admits that the spores vary in size and the number of 
meshes, the largest specimens bearing the largest spores with the 
greatest number of meshes, but he says he has found similar spores 
on smaller double specimens. I have not found any American 
spores having as few areolae (6-12) as he describes in O. vulgatum; 
ours often have as many as 25-30 areolae on one surface of the 
spore, and the outline appears as a series of indentations rather 
than a papillose surface, as seen in the European specimens. I 
have found that in O. avenarum the surface is marked by irregular 
warty protuberances, almost all traces of the polygonal areolae of 
O. vulgatum being lost, and the surface less regularly pitted like a 
thimble as it is in O. vadgatum. I have also seen small forms of 
O. vulgatum approaching O. arenarium which had the spores like 
the former. 
O. vulgatum has a wide geographical range, having been 
collected at various stations in Europe, and also showing much 
variation according to Prantl. It has been found in Western 
Asia; Prantl has not credited it to Japan, but there is a specimen : 
in the Gray Herbarium collected in 1891 in Japan, which certainly 
