66 N. Bancroft. 
Since Worsdell formulated his theory of the Medullosean 
origin of Cycadean vascular structures, the discovery of Sutcliffia 
has shed new light on the Medulloseas as a group, showing that it 
possessed monostelic forms within itself. The description of the 
new form has carried with it a new view of the origin of the Cycads. 
A tentative statement was made by Scott in the concluding chapter 
of the “ Studies ” to the effect that “ on the whole of the evidence 
available it appears likely that some at least of the Cycadophyta 
may have been derived from plants resembling the Medulloseae 
Fig. 20. —A, representation of method of derivation of the numerous, 
separate, collateral bundles of petiole of Cycads from the single large concentric 
bundle of petiole of Lyginopteris, etc. (transverse section). (After Worsdell, 1906). 
B, Stangcria parodoxa. Transverse section of vascular system of petiole, 
showing lateral fusion of bundles, cf. grouping of bundles in A. (From 
Worsdell, after Matte). 
(Neuropterideae) in certain characters, though probably with mono¬ 
stelic rather than polystelic structure of the stem ” (14, p. 650). 
Miss de Fraine has elaborated this view, at the same time criticising 
WorsdelPs theory (3). She points out that in the light of recent 
research, reliance for ancestral characters upon the structure of 
the cotyledonary node and flowering axis is inadvisable ; and 
concludes that the origin of Cycads from polystelic ancestors is 
“ not yet satisfactorily proved.” Miss de Fraine suggests as an 
