_ Jurassic plants from Yorkshire 109 
| ingens with the male sporophylls borne below the female strobilus. 
This may be regarded as the normal type of bisexual structure in 
the Bennettitales, but I do not consider the present specimen as 
conforming to it. 
In some specimens of the female flowers of W. gigas we see 
the female strobili still attached to the peduncle and surrounded 
by many overlapping bracts, without any trace of our cup-shaped 
microsporophylls. Had such a structure been originally present 
it must have become loosened from the axis and slipped over the 
ovuliferous portion, becoming free and independent without 
breaking up. But there are no signs that the bases of these 
eup-like united microsporophylls separated or broke up to allow 
them to slip over the female strobilus. If the analogy with W. 
spectabilis is at all complete, our male flower would have possessed 
a somewhat narrow stalk and the type of origin just suggested 
would be impossible. 
Moreover the curious urn-shape of the cup suggests a structure 
which was freely exposed during its development and not en- 
closed by ensheathing bracts in the circular buds so well known 
in this species. There are in the matrix of our specimen no 
traces of bract-like structures, and had any number of them been 
originally present, the longitudinal section through the male 
flower would have probably presented a more or less circular 
form. 
The second view of the possible origin of the microsporophylls 
would see them as arising above the ovulate portion of the flower 
and in the position in which Lignier has placed his ‘appendice 
infundibuliforme.’ There are however serious objections to this view. 
In the first place the bisexual Bennettitalean flowers already known, 
1e. Cycadeoidea, Wirelandiella and Williamsomella, all have their 
microsporophylls below the megasporophylls, and no specimens are 
known in which the microsporophylls were produced in the superior 
position. In the second place the evidence for the existence of 
such a structure as Lignier’s infundibuliforme appendage is very 
meagre, and I have myself seen no specimen which shows any 
trace of such a structure. ‘lhe apex of the strobilar axis without 
such an appendage may be closely compared with that of the new 
Walliamsoniella and also with an undescribed species of William- 
sonia in my collection. Another objection which may be tentatively 
advanced, is that a flower of Williamsonia, with the male disc 
attached above the seed zone, would be a very top-heavy and 
rather uneconomical form. 
The third view of the origin of the structure here described is 
that it was a separate ‘flower’ produced on its own stalk, and 
independent of the female strobilus. The unisexual theory of the 
flowers fits in much better with the known facts than the other 
