270 
Palaeontologie. 
are first met with in the Mesozoic Cycadophyta , with which the 
present paper deals. Some of the Mesozoic Cycadophyta possessed 
reproductive organs of a much higher Organisation than those of 
any living Cycads. This is one of the many facts in palaeontology, 
which shows that evolution is by no means the obvious progression 
from the simple to the complex. 
After reviewing some of the Mesozoic Cycadophyta which seem 
to have been essentially similar to the recent Cycads , the author 
passes to a full account of the structure of the English and American 
Bennettiteae, which is illustrated by 4 plates. The structure of the 
Bennettitean flower, elucidated recently by Wieland, may bebriefly 
recapitulated as follows. The centre is occupied by the gynaecium 
seated on the convex receptacle, and consisting of numerous long- 
stalked ovules, imbedded among the interseminal scales. Surroun- 
ding this central body is the hypogynous whorl of stamens, fused 
below to form a tube, and expanding above into the pinnate sporo- 
phylls, bearing very numerous compound pollen-sacs or synangia. 
The whole is surrounded by an envelope of spirally arranged bracts 
springing from the upper part of the peduncle. The general arran- 
gement of parts is manifestly just the same as in a typical angio- 
spermous flower, with a central pistil, hypogynous stamens and a 
perianth. The resemblance is further emphasised b}^ the fact, long 
known, that the interseminal scales are confluent at their outer ends 
to form a kind of pericarp or ovary-wall. The seed is exalbuminous 
and the embryo dicotyledonous. Thus the comparison with the flo- 
wers of the Magnoliaceae and Ranunculaceae is a closs one. In cer- 
tain respects the Bennettitean flower was in advance of these more 
primitive Dicotyledons, as seen in the arrangement of the stamens 
which have abandoned the spiral phyllotaxis of the other organs to 
ränge themselves in a definite whorl, while at the same time their 
stalks are fused into a tube, the monadelphous condition. 
Probably the Bennettitean flower possessed some form of colour 
attraction, and may have had some relation to the insect life of 
the period. 
The author agrees with Wieland that the flower of Bennettites 
is a single axis, bearing fertile and sterile organs of a foliar nature, 
though the homologies of the seed-pedicels and interseminal scales 
present, in comparison with the carpellary structure of Angiosperms, 
a difficult problem. 
The Bennettiteae have also affinities in other directions. While 
the gynaecium is essentially Gymnospermic, the stamens, by their 
structure and form, carry us back to the sporophylls of a Fern, so 
tlie flower of the Bennettiteae as a whole may be almost said to 
bridge the gulf between the Cryptogams and the higher Flowering 
Plants. The Fern-like characters have probably come to the Bennet¬ 
titeae not directly from true Ferns, but through the intermediate 
group of the Palaezoic Pteriodosperms. The fact that the pollen-grains 
are borne in compound pollen-sacs or synangia like those of the 
Marattiaceous Ferns is one of great signifieance. But the Bennettiteae 
where probably not derived from the Marattiaceae , though an indi- 
rect affinity may have existed. 
The Bennettitean flower presents an extraordinary combination 
of characters, characteristic of the Angiosperms, Gymnosperms and 
Ferns. The complexity of this earliest known type of a true flower 
indicates the probability that the evolution of the Angiospermous 
flower was a process of reduction. There is thus no longer any pre- 
