On Gymnosperntous Seeds. 147 
This seed, best known from Williamson’s full and admirable 
description 1 of L. ovoides , occurs in beautiful preservation in the 
calcareous nodules of the Lower Coal Measures. It is a small seed 
(5 or 6 m.m. X 4 m.m.) belonging to the type with adnate integu¬ 
ment and nucellus. It is only in the pollen-chamber region (about 
l the whole length of the seed) that these parts are free from one 
another. The relations of the parts in longitudinal section are 
shewn in Williamson’s figures 2 . 
The free apex of the nucellus, the “ lagenostome ” of Williamson, 
is transformed into a pollen-chamber. The nucellar epidermis 
persists as the wall of the chamber (pew in text fig. 4 ) whilst the 
cavity of the pollen-chamber arises by the breaking away of the 
central tissue from the wall. This central mass stands up as a cone 
of tissue (cc, fig. 4 ) on the floor of the chamber, the actual pollen- 
chamber, in which pollen-grains are frequently found, is in a bell¬ 
shaped crevice (pc in fig. 4 ) which communicates with the exterior 
at the micropyle. This form of pollen-chamber is very remarkable 
and perhaps unique. 
The wall of the pollen-chamber is longitudinally ridged, these 
ridges are seen in the transverse section as projecting cusps. The 
central cone which has become separated from the wall in the 
development of the pollen chamber has corresponding radial pro¬ 
jections. In the specimen upon which the accompanying diagram 
is based, nine symmetrically placed ridges are present. 
Surrounding the pollen-chamber is the very complicated integu¬ 
ment, consisting of an outer zone ( t ) which is circular in transverse 
section, and an inner zone consisting of nine symmetrically disposed 
chambers which are separated from one another by strong radial 
plates. The internal angle of each chamber is convex and their 
internal containing-walls form collectively a fluted membrane, the 
relations of which are well seen in fig. 4 . This membrane (c) was 
termed by Williamson the “canopy.” As the figure shews, the 
cusps or ridges of the pollen-chamber wall interlock with the grooves 
between the convexities of the canopy. The unshaded space (g) 
between these two membranes is the natural gap between the 
nucellus and integument, these two portions of the seed being, of 
course, free from one another in this region. As regards the mor¬ 
phological nature of the canopy and radial plates, the provisional 
view may be taken that they represent an inner layer of the testa 
1 On the Organisation of the Fossil Plants of the Coal-measures. 
Pt. VIII., Phil. Trans. 1877, pp. 233-243, and figs 53-5 
2 loc. cit, figs. 60-69. 
