Pteridosperm Anatomy. 
4i 
represented on the south-facing side of the gorge. Further up the 
gorge this gives place also to the Pignon-Juniper association and 
then to Pignon alone. Populus treniuloides is abundant along the 
riverside. Further up still the gorge opens out and Douglas fir, 
Engelrnann spruce and aspen appear on the upper slopes of the 
valley. Eventually a broad valley is entered, sub-alpine meadow 
containing much Potentilla fruticosa with Picea Engelmanni and 
Pinus Murray ana (the lodge-pole pine) which is absent from the 
Pike’s Peak region, though it forms a well-marked altitudinal zone 
further north. Tennessee Pass, crossing the Continental divide at 
10,246 feet, was reached about dusk and here are close stands of 
lodge-pole pine—perhaps fire relicts—among great stretches of bare 
grass-covered mountain. 
(to be continued). 
PTERIDOSPERM ANATOMY AND ITS RELATION TO THAT 
OF THE CYCADS. 
By N. Bancroft. 
[With Twenty Figures in the Text.] 
HE question of the origin of the Cycadophyta is one of great 
interest, and regarded merely from an anatomical stand¬ 
point, it has provided ample material for discussion. 
There are two main views concerning the origin of Cycadean 
vascular anatomy—first, that advanced by Scott (14, pp. 648-650) 
deriving it from the type possessed by Pteridosperms of the 
Lyginopteridean alliance ; and secondly, that deriving it from the 
type exhibited by the Medullosean alliance, this latter thesis being 
upheld principally by Worsdell (23). There is much evidence in 
favour of both views, but this is only to be expected since the 
Lyginopteridean and Medullosean types of anatomy may be shown 
to be closely related through the simplest forms of each, the 
discovery of Sutcliffia (13) having been of great significance in this 
connection. Dr. de Praine’s recent description of Sutcliffia (3) is 
concluded by a third hypothesis with regard to the origin of 
Cycadean anatomy; this may be considered as a modification of 
