Notes on Recent Literature. 
361 
hexagonal areas of the interseminal scales with the micropylar tubes 
projecting among them. Two species of female “ flowers ” differing 
in general form have been distinguished, one having a spherical, the 
other a pyramidal external shape. By treatment with acid the form 
of the cells of the interseminal scales and the micropylar tubes are 
clearly seen. It is not known whether the flowers of all the 
Williamsonias were surrounded with a perianth-like ring of bracts ; 
in the original W. gigas this was doubtless the case, and in the beds 
containing the other strobili numerous separate bract-like structures 
of doubtful affinity are found, but no specimen is yet known which 
has such bracts in place. 
Professor Nathorst’s work and my own observations lead to the 
conclusion that plants allied to Williamsonia formed a considerable 
part of the Lower Oolitic Flora of Yorkshire. It is probable that 
most of the Jurassic Cycad-like fronds should really be associated 
with these plants, though at present the only evidence of actual 
connection is found in the case of Wielandiella ( Anomozamites ). 
Professor Nathorst holds the view, however, that it is at present 
wise to retain the old form-generic names for the leaves where 
actual connection has not been proved. He therefore rejects the 
use of the term Williamsonia as applied to the fronds usually 
known by that name, and retains the original designations of Ptilo- 
phyllum and Zamites for them. 
One of the most interesting results which this work has 
furnished, concerns the number and arrangement of the micro- 
synangia. While in W. spectabilis these are very numerous and 
rather irregularly scattered over the sporophyll, yet they are 
apparently not so plentifully produced as in Bennettites. In W. 
whitbiensis, however, the number is very considerably reduced. 
The lower ones are sterile, and in the restoration given, there are 
about eighteen synangia to each sporophyll. If it is safe to draw 
any conclusions from Williamson’s “ carpellary disc ” it would 
appear that the functional sporangia were reduced to two on each 
sporophyll. 1 In a yet undescribed allied form ( Williamsoniella 
coronata) in my collection, there are five or six synangia on each 
sporophyll, so that the smaller number is not exceptional. The 
“flowers” of Wielandiella also exhibit an advanced stage in the 
reduction of the microsporangia. Here the latter are few in 
number, sessile and arranged in the form of a ring or flange 
round the lower part of the receptacle. They seem to be situated 
directly on the axis and show no traces of sporophylls. They can 
therefore be compared somewhat closely with a whorl of sessile 
stamens, in which the anthers are more or less united. Whether the 
Bennettitean type of microsporophyll is more primitive and the 
Williamsonia whitbiensis type a derived form, is largely a matter of 
conjecture, but there seems to be some evidence in favour of such 
a view. It is, however, clear that the excellent work which 
Professor Nathorst has done will lead to interesting results. 
H. H. T. 
1 This view is adopted by Schuster, who has recently described 
Weltrichia , another genus of the Bennettitales, and has tried to 
trace the actual steps in the evolution of the Ranalian flower 
from the Bennettitalean strobilus. Schuster, K. Sv. Vet, 
Akad- Hand. Bd. 46, No. 11, 1911, 
