9 8 
F. \V. Oliver. 
width. The compact layer of the testa, has a diameter of ^ min., 
but its preservation is very imperfect and it is only possible to say 
that it was probably composed of close-fitting fibrous or sclerotic 
cells. Peripherally it is overlaid by two or three layers of quite 
thin-walled, iso-diametric, parenchyma cells, which, being without 
external delimitation, very likely represent but a portion of a more 
extensive tissue (photo. 3, St.) These cells could hardly be described 
as “cellules rayonnantes,” so it may be inferred we are dealing here 
with something not represented in the specimens examined by 
Brongniart. His “cellules rayonnantes” correspond perhaps to a 
layer of palisade belonging to the sclerotesta, but not recognised in 
our specimens owing to the condition of preservation. 
The differentiation shewn by the testa in this seed is consistent 
with the view that Trigonocarpus was a drupaceous seed with a hard 
shell or sclerotesta and an outer sarcotesta. 
Since the two sections which we have obtained of this seed 
are both longitudinal, and neither of them coincides with the plane 
of any of the three sutures, there is nothing to add to the statements 
cited above. The identification depends on the form and 
dimensions of the longitudinal sections. 
The nucellus tapers slightly towards the apex, which is modified 
as a pollen-chamber, though no pollen-grains are present in our 
specimen. The true cavity of this chamber is obviously exaggerated 
by the contraction of the prothallium, a not unusual feature in 
seeds of this period. 1 The original floor of the pollen-chamber is 
shewn at S, photo. 3. Above the pollen-chamber, in the more 
nearly median section (photos. 1 and 3) remains of the base of a 
nucellar beak are present; but whether this structure was long and 
tubular as in Steplianospennum, or whether on the other hand it 
ended abruptly, must remain undecided as the distal portion is 
wanting in our preparation. However this may have been, our 
seed resembles Steplianospennum in possessing a loose flange or 
collar round the base of the nucellar apical process (photo. 3, C). 
Of several possible interpretations of this collar the most probable 
is that it represents the epidermis that has become separated from 
the other tissues of the roof of the pollen-chamber. The causes of 
its detachment must be sought in the processes of decay that 
obtained on the death of the seed, combined perhaps, with a local 
induration of the epidermal tissues and a jamming of the 
nucellar beak in the micropyle.- 
1 Oliver, loc. cit., P1.4r, photo 2. 
2 Loc. cit, p.. 372. 
