Trigonocarpus Shorensis , sp. nov. 
59 
V. The Nucellus. 
The total length of the free nucellus, from the point of junction with the 
testa to the base of the pollen chamber, was about 18 mm., and its diameter 
in the widest region about n mm. As the cavity in this part was some 
15 mm. in width, there is left a space of 2 mm. all round for which to account. 
The question of an inner flesh has already been discussed, but in any case 
these dimensions for the nucellus are probably much too small, owing to 
post-mortem contraction. 
The general outline of the nucellus conformed closely to that of the 
cavity within which it stood, following the same lines until near the base of 
the micropyle, where the nucellar tissue curved sharply inwards to the 
insertion of the pollen chamber. 
Disregarding this latter structure, the conformation was that of a sharply 
pointed egg with its narrower end directed downwards and attached to the 
sclerotesta, whilst the blunt free end was surmounted by the pollen chamber. 
The nucellar tissue is in most cases either lacking altogether or ill pre- 
served, but fortunately, in the transverse series S. 33, a to S. 33, d y the structure 
is beautifully shown, though considerably contracted. In the uppermost of 
the series the nucellus occupies a one-sided position which is in part due to 
the slight obliquity, but no doubt in the main to displacement through 
asymmetrical shrinkage. 
In the second of this series the nucellar tissue is seen surrounding the 
chalazal bundle. As already described, this consists of parenchymatous 
tissue, of which the cells are thin-walled and vary in size from about 
o-oi to 0*050 mm., interspersed with secretory ducts, the largest of which are 
at the periphery and measure about 0*07 mm. in diameter. This ring of 
tissue is only o*2 mm. in width, but from its ragged edge was evidently 
much more extensive in life. 
Owing to the shrinkage of the soft underlying tissue, the much less 
contractable epidermis is thrown into numerous folds, but the projections 
thus formed do not, as in Trigonocarpus Parkinsoni , correspond to underlying 
vascular strands, 1 but to radial files of secretory elements (PI. V, Fig. 20, m. s. 
and n.r,). Taking the distance from the edge of the megaspore cavity to 
the summit of these ridges as the basis of our estimate, the thickness of the 
nucellar tissue must have been, near the chalazal end of the seed, at least 
c*3 mm., though above this level it diminished slightly and then remained 
of constant width up to the base of the pollen chamber. At the outside 
there was a very strongly defined epidermis, (S. 33, c y PI. V, Pig. 2c, n.e.), the 
cells of which (0-05 mm. radial x 0*03 mm. tangential) stand out all the more 
clearly since their contents are preserved as dark carbonaceous masses that 
have contracted away from the cell walls. Where, owing to the contortions 
1 Scott and Maslen, loc. cit. , p. 119. 
