Hickling . — The Anatomy of Palaeostachya vera . 379 
sporangia in a whorl. The four belonging to one sporangiophore were set 
so that two were inner and two outer, or, as would perhaps be more 
accurate, two superior and two inferior. The whole of the sporangia were 
closely packed so as to fill completely the space enclosed between the 
bracts and the axis. Consequently as seen in radial longitudinal section 
they were roughly triangular, the outer ones base downwards, the inner 
base upwards (Text-Fig. 1). Seen in transverse section they appear as 
truncated wedges, the radial length of which will obviously vary with the 
position of the section in relation to the nodes (Text-Fig. 2). 
The wall of the sporangium is exactly similar to that found in 
Calamostachys. It consists of a single layer of cells which are charac- 
terized by ‘ buttressed ’ walls, such as are familiar in the latter genus 
(Fig. 17). It is difficult to distinguish between buttresses and radial walls } 
and consequently to make out the real form and size of the cells. As far 
as can be made out these cells are brick-shaped, or lozenge-shaped in 
surface view, about 35 n in the shorter and 100 fx in the longer diameter. 
The thickening was practically confined to the inner and radial walls 
of the cells. I have seen no indications of a tapetal layer, but this could 
scarcely be expected in view of the state of preservation and ripeness of 
the cones. 
Williamson, 1 in his description of the cone, makes a point of the 
partial or entire absence of the sporangial walls in some sections, and 
regards this as probably due to resorption as a means of liberating the 
spores in the absence of elaters. This seems to me quite an unnecessary 
assumption, in view of the fact that decomposition had proceeded to the 
extent of removing nearly all the soft tissue in the cone. 
Attachment of the Sporangia. No details of this can be given, but the 
main fact is certain, that they were borne on the under surface of the peltate 
expansion of the sporangiophore, near its periphery. 
The Spores. There is no indication of heterospory, no variation in 
the size of the spores in one or in different sections being noticeable. The 
spores are normally circular in form, with a diameter of about 80 /x. 
A characteristic feature, in the existing material, is that each spore shows 
two distinct walls, separated by an interval, besides which there is generally 
a large rounded or irregular dark mass in the centre. 
The outer walls of adjacent spores are closely packed together, and 
consequently polygonal in section. The inner, which has a diameter about 
three-quarters that of the outer, is usually round. The most probable inter- 
pretation appears to me to be that the two walls merely represent the 
extine and intine, the latter having shrunk away from the former owing to 
a process of plasmolysis which would not improbably take place in the 
peaty mass of material before or during its calcification. In the same way 
1 Williamson, ’87, p. 53 . 
