139 
Temp sky a ( Endogenites ). 
the specimens frequently taper to a pointed termination, and 
the external surface may be covered over with a layer of 
coaly substance representing carbonised tissue. The roots 
are of the diarch type, and the petiole structures are charac- 
terized by a horseshoe-shaped vascular band. (The central 
vascular axis possibly of the Prctopteris form.) 5 
The specimen to be described is a water-worn piece, that 
was picked up below the cliffs just east of Hastings. The 
vascular bundles of the roots have nearly all disappeared, 
and their place is mostly represented by a clear area. This 
consists of quartz 1 surrounding a central cavity, or occasionally 
without any cavity. There is a certain amount of carbonised 
material in the cortical region of the roots. It is sometimes 
arranged so as to give the appearance of the cell-walls in 
a badly preserved tissue ; but comparison of different parts 
of the section proves that this appearance is often mis- 
leading. 
In one section there are two or three hundred spores 
aggregated in a slightly lobed mass which is penetrated by 
two roots (?) ; several spores also occur scattered at some 
distance from it. From their form and structure they are 
probably fern spores, and their arrangement suggests a large 
sporangium or a sorus. The spores are yellowish brown in 
colour, about 65 // in diameter, and vary in shape from 
spherical or oval to bluntly tetrahedral (see Figs.). This 
apparent variation is, of course, partly due to the varying 
positions of the spores. A considerable number of the spores 
must have been shrunk before the specimen was mineralised ; 
thus causing irregularities of form, such as Fig. 4 exhibits, 
where the spore is shown in section. The wall of the spore is 
in nearly all cases strongly pitted, and the thickenings take 
the form of bars, which run roughly parallel with one another, 
and fuse at intervals. There is a good deal of variation in 
the form of the thickenings, but Fig. 1 may be taken as 
a typical appearance of the spore when viewed from the 
1 Dr. W. F. Hume has kindly examined a slide and determined that this is 
secondary quartz, formed in the cavities by subsequent infiltration. 
