7 2 ° 
Notes . 
classification, on evolutionary lines , of the great groups of the vegetable 
kingdom. Now the distinguishing feature of the great group, the 
Angiosperms, which to-day head the evolutionary line, is the character 
of one set of its essential organs, the female sporophylls or carpels, 
which are dorsiventral in structure and bear the ovules marginally 
or on their ventral surface, and are, moreover, closed together over 
the ovules to form the characteristic ovary. But Bennettites shows 
absolutely no indication of such an advanced structure in its essential 
organs, the sporophylls, which remain primitively radial in structure, 
bearing the ovules in a terminal position; the angiospermous condition 
(using this term as in no sense referring to the ‘ Angiosperms ’) being 
brought about solely by the unessential organs : the interstitial bracts 
or sterile sporophylls, and the large ensheathing bracts springing from 
the base of the entire cone; these together form an adequate pro¬ 
tection for the seeds. That modern Cycadean plants still retain the 
primitive radial symmetry of their sporophylls here and there may be 
seen in the female sporophylls of Cycads generally (although in these 
the ovules have become relegated to a marginal, or rather a sub-dorsal 
position), in the radially-constructed short ovuliferous segments of the 
female sporophyll of Cycas, which bear the ovules in a terminal 
position, and in the female cone of Ginkgo , which, as clearly observed 
in abnormal cases, produces the ovules terminally on radially- 
constructed sporophylls. 
The conclusion which is, therefore, to be drawn, is this : that the 
fructification (or cone) of Bennettites Gibsonianus , Carr., is to be regarded 
as more primitive in structure than that of modern Cycads owing to the 
fact that its sporophylls possess both a radial symmetry of structure 
and (what is, probably, a necessary condition) bear the ovules in 
a terminal position. This view of the matter will save the incongruity 
of a plant, like the one under consideration, possessing a vegetative 
structure (as of the stem) considerably more primitive and a fructi¬ 
fication much more advanced than that of modern Cycads. And 
I would further point out that complexity of differentiation in a 
structure (as in the cone of Bennettites) is by no means necessarily 
synonymous with an advance in evolutionary development, and this for 
the reasons above given. 
In conclusion, the relationships between the structure of the cone of 
Bennettites , of the cone of modern Cycads, and of Ginkgo , may be 
indicated, on the lines laid down above, in tabular form, thus ; — 
