PELLAEA GLABELLA AND ITS SEGREGATES 81 
sists of a central mass, often cleft along the median 
plane, and of lateral wings extending outward and to- 
wards the ventral side of the stipe. In P. glabella these 
wings are relatively large and widely extended, so that 
the xylem bundle has in cross-section the outline of a 
very flat V. The whole vascular bundle is somewhat 
reniform in cross-section, or merely flattened on the 
ventral side. In P. Suksdorfiana the wings of the xylem 
are somewhat shorter, and at first extend horizontally, 
then curve sharply towards the ventral side of the stipe, 
and may even be completely inflexed at the tip. The 
whole vascular bundle has a distinctly reniform cross- 
section. In P. pumila the wings of the xylem are still 
shorter, and directed towards the ventral side of the 
stipe, the xylem mass is very compact, and the whole 
vascular bundle is nearly circular in cross-section. 
In my earlier paper I cited the specimens of the two 
western species which are in the Gray Herbarium. The 
following specimens from the National Herbarium (N) 
and the Herbarium of the University of Minnesota (M) 
have been examined in the preparation of the present 
paper: 
Pellaea pumila: Sovra Daxora; Bull Springs west 
of Custer, P. A. Rydberg, no. 1191 (N); Deadwood, 
crevices in white rocks, C. R. Ball, no. 1688 (N). 
Wyominc: Laramie Hills, Albany Co., A. and E. 
Nelson no. 6837 (N); Loomis Creek, Natrona Co., dry 
cracks in cliffs, Leslie N. Gooding no. 183 (N two sheets) ; 
Mammouth Hot Springs, Yellowstone Park, dry eracks 
in cliffs alt. 6000 ft., F. H. Burglehaus (M two sheets, 
and N . 
Monvrana: Bozeman, limestone cliffs 5000 ft., J. W. 
Blankinship no. 638 (N); Belt Mts., R. S. Williams no. 
241 (N). 
Auperta: Banff, limestone cliff at base of Tunnel 
Mt. F. K. Butters (M). : 
Pellaea Suksdorfiana: Arizona: San Francisco Mts., 
9000 ft., D. T. MacDougal (M); Jacob Lake, Kaibab 
