Notes. 
7i5 
integument. The outer layer of the sporangial wall has the columnar 
or palisade-like structure characteristic of Lepidostrobus; it is lined 
by a more delicate inner layer, which may be several cells thick. 
So far the structure is simply that of a Lepidostrobus with rather 
thick-walled sporangia. 
Within the sporangial cavity, the membranes of the megaspores are 
usually preserved; a single large megaspore almost fills the sporan¬ 
gium, but smaller, abortive spores, with thicker walls, are also present. 
Some specimens show that three of these abortive spores were present 
in each sporangium. It appears, then, that a single tetrad was 
developed in each megasporangium, and that of the four sister-cells 
one only came to perfection, constituting the functional megaspore. 
In one specimen, discovered by Mr. Wild, the strobilus is in a more 
advanced condition. In its upper part the sporophylls simply bear 
sporangia, as above described, but lower down in the cone these are 
replaced by integumented, seed-like structures, identical with the 
detached bodies called Cardiocarpon anomalum by Williamson. 
The structure of this strobilus is sufficiently well preserved to show 
that the anatomy of the axis agrees with that of the less mature 
specimens, and, as the tissues are more completely formed, exhibits 
the Lepidostroboid characters even more clearly. 
Mr. Wild’s specimen, then, demonstrates that the Cardiocarpon 
anomalum of Williamson was borne on a cone with all the characters 
of a Lepidostrobus , and that it represents the matured condition of the 
megasporangium and sporophyll. 
The detailed comparison of specimens in the young and the mature 
condition has shown the nature of the change which converts the 
megasporangium, together with its sporophyll, into a seed-like organ. 
The nucellus of the latter retains almost unaltered the structure of the 
megasporangial wall, with its columnar layer. In the sporangial cavity 
the single large mega spore, accompanied by its abortive sister-cells, 
is present as before. A thick integument has, however, grown up 
from the sporophyll, completely overarching the megasporangium, 
except for a narrow crevice left open at the top. When seen in a 
section tangential to the strobilus as a whole, this crevice is cut across, 
and presents exactly the appearance of a micropyle; in reality it 
differs from a micropyle in being a narrow slit, extending almost the 
whole length of the sporangium, in the radial direction, whereas the 
micropyle of an ordinary seed is a more or less tubular passage. 
