132 Transactions of the Society. 



find a much more primitive arrangement ; no cone at all is 

 differentiated, but the carpels are borne directly on the main stem 

 of the plant, in rosettes alternating with those of the vegetative 

 leaves ; thus there is no special reproductive axis, but the sporo- 

 phylls spring from the axis of the plant as a whole, just as in an 

 ordinary fern. The carpels themselves are lobed and extremely 

 leaf-like, bearing as many as six ovules in many cases, though in 

 one species the number is reduced to two. Thus in Cycas the 

 seeds are borne on organs still obviously leaves, and nothing of the 

 nature of a flower is differentiated. No other living seed-plant is 

 so primitive as this, but the Oycads as a whole are undoubtedly 

 the most primitive family of present-day Spermophyta, as is most 

 strikingly shown in their cryptogamic mode of fertilisation by 

 means of spermatozoids, which they share with Ginkgo alone 

 among Seed-plants. 



When we go back to the Mesozoic age we might, on what one 

 may call the elementary view of evolution, expect to find the 

 Cycadophytes which were so abundant at that period, still simpler, 

 and still nearer the cryptogamic condition than the members of 

 the class which have come down to our own day. But this is by no 

 means the case ; there were, no doubt, a certain number of Cycads 

 in Mesozoic times which were about on the same level of organisa- 

 tion as their living representatives, but the great majority, so far as 

 the available evidence shows, attained a much higher organisation, 

 at least in their reproductive aiTangements, far surpassing any of 

 the Gymnosperms now known to us. This is one of the many facts 

 in palaeontology which show that evolution is by no means the 

 obvious progression from the simple to the complex which many 

 people have imagined. Just as the Lycopods and the Horsetails 



EXPLANAO^ION OF PLATE VII. 



Fig. 2. Bcnndtitcs Gibsoniamis. A. Diagram of the fructification iu radial 

 section, re, receptacle ; br, bracts, overlapping at the top of the fruit ; 

 s, seeds, seated on long pedicels, and each containing a dicotyledonous 

 embryo ; p, dilated ends of the interseminal scales (which should be 

 more numerous) forming the "pericarp." B. Ramenta, like those of 

 Ferns, in transverse section, x about 15 diam. C. Transverse section 

 of a seed, i, the double-layered testa ; n, membrane representing the 

 nucellus ; ct, the two cotyledons of the embryo, showing the young 

 vascular bundles, x about 12 diam. D. Somewhat oblique longitu- 

 dinal section, passing through the micropyle of a seed, em, radicle- 

 end of embryo ; r, apex of radicle ; c, remains of endosperm (?) ; rn, 

 micropyle, obliquely cut ; i, outer layer of testa ; p, part of pericarp ; 

 c, f, crevices in pericarp, corresponding to the limits of the interseminal 

 scales composing it. x 20 diam. From Scott's "Studies in Fossil 

 Botany." 

 ,, 3. Bennettitcs Gibsonianus. Longitudinal section of seed, showing the 

 dicotyledonous embryo, c, c, the two cotyledons ; a, apex of plumule ; 

 b, radicle, x 12 diam. Photograph, from Scott's " Studies in Fossil 

 Botany." 



