82 AMERICAN FERN JOURNAL 
range which corresponds entirely with the distribution 
of P. glabella as here recognized, taken together with a 
western variety of that species, while P. atropurpurea 
is not known in either Wisconsin or British Columbia. 
Typical Pellaea glabella appears not to cross the 
plains, but in the Black Hills, northern Rocky Moun- 
tains and westward, there are two forms which are s0 
closely related to this species that it seems best to con- 
sider them as varieties of it. 
One of these is P. glabella var. occidentalis (E. Nelson),’ 
a plant which has already given a good deal of trouble 
to western systematists and collectors, having beet 
variously cited as P. Breweri, P. atropurpurea, as a neW 
variety of the last mentioned species, and as a neW 
species. That it is much more closely related to P. 
glabella than to P. atropurpurea is shown by the glabrous 
stipes, the form and structure of the scales, and the 
shape of the leaflets. In fact, in both of the last met 
tioned characters, it stands at one extreme of a series; 
and P. atropurpurea at the opposite extreme. ; 
It differs from typical P. glabella in its smaller size, 
having simpler and somewhat less coriaceous fronds 
with broader and less revolute fertile pinnae, in haviné 
shorter cells in the scales, and in having somewhat 
smaller spores, which are of a more uniformly tet! 
hedral shape. In size it varies from a height of about 
2 cm. in the case of very depauperaie individuals, to4 
maximum height of about 15 cm., apparenily rarely 
exceeding 1 dm., while mature planis of typical P. gla- 
bella are rarely under 1 dm. high. 
The fronds of the variety are almost always simply 
pinnate, though the lowest pinnae are rarely temaleY 
: o2A GLABELLA E. Nelson) 
new comb. Mett. ex Kuhn, var. occidentalis ( 
erst atropurpurea occidentalis E. Nelson, Fern Bull. 7? 30. 1889- 
hin be Ry db. Mem. New York Bot. Garden, 1: 4. 1900. 
@ occidentalis (E. Nelson) Rydb. loc. cit., 466. 1900. 
