8 Seward: The Jurassic Flora of Yorkshire. 
period and in the earlier days of the Cretaceous epoch there 
existed in many parts of the world, more especially in North 
America, numerous species of Cycadean: plants which, in the 
form of the leaves and in anatomical characters, agreed closely 
with recent Cycads. But, despite the striking likeness between 
the vegetative organs of the fossil and recent plants, the great 
majority of the former possessed reproductive organs differing 
widely from those of existing Cycads. The stems bore lateral 
fertile branches ending in oval flowers characterised by a conical 
receptacle on which were borne numerous slender stalks, some 
terminating in single seeds, while others, known as interseminal 
scales, were sterile and extended beyond the seeds which they 
partially enclosed by their distally expanded ends. The 
researches of Mr. Wieland in America have demonstrated that 
at least in many instances, the flowers of these extinct plants 
were bisexual, the male organs having the form of pinnate 
leaves clustered round the base of the conical receptacle to 
which the female organs were attached. The male reproductive 
cells were contained in sacs comparable to the sporangia of 
certain recent tropical ferns, whereas the female organs have 
the structure of complex seed-bearing flowers. The important 
point is that in their reproductive organs the majority of the 
Mesozoic Cycads differed enormously from any recent species. 
As yet we have not obtained a single specimen of a petrified 
Cycad from the Yorkshire beds, but casts and impressions of 
portions of flowers are by no means uncommon. Specimens 
of such casts were figured by Young and Bird in 1822, and 
spoken of by them as specimens of the true Artichoke (Cynara 
integrifolia). A comprehensive account of these fossils was 
published by Williamson in 1870 in which he expressed the 
opinion, now generally accepted, that the specimens des: ribed by 
Young and Bird, and subsequently named by Carruthers 
Williamsonia, are the flowering shoots of a Cycadean plant, the 
leaves of which are represented by the pinnate fronds called by 
Lindley and Hutton Zamutes gigas. Though Williamson believed 
that the Yorkshire examples of Williamsonia included both male 
and female flowers, the occurrence of undoubted male flowers was 
not proved until last year when Dr. Nathorst succeeded in finding 
in the Whitby beds portions of spore-bearing organs. My object 
is not, however, to discuss the structure of the fertile shoots of 
Williamsonia, but to draw attention to the need for further 
search, which may enable us to decide to what extent the 
Yorkshire specimens agree with those of the closely-allied 
genus Bennettites, instituted by Carruthers for a remarkable 
stem from Lower Cretaceous beds in the Isle of Wight, bearing 
flowers sufficiently well preserved to show the structure of the 
small embryos in the seeds. 
(To be continued ). 
Naturalist, 
