Scott and Hasten . — The Stricture of Trigonocarpus . 119 
a ‘ wing ’ comparable in length and form with one from the micropylar 
region. At the same time the ‘ wings ’ in the micropylar region are much 
more symmetrically developed than elsewhere. We think that, on the 
whole, the evidence favours the existence of real wings, but the examination 
of specimens with still better preservation of the outer part of the testa will 
be necessary before the presence of wings can be positively affirmed. 
The Nuceltus and Pollen- Chamber. 
In all our longitudinal sections of Trigonocarpus Par kinsoni the nucellus 
stands up freely from the base of the seed, with a space between it and the 
sclerotesta (see PI. XII, Figs. 12 and 13). The width of this space varies 
considerably in different specimens, and in some cases it is quite narrow. 
In a fairly median longitudinal section (941 S.) in which the nucellus does 
not appear to have suffered much displacement or contraction, the average 
width of the space is only -25 mm. In most slides contraction has taken 
place, and the space is consequently much greater. 
On the assumption of an ‘ inner flesh’ (p. 110) this space would have 
been partly occupied, so that if, as seems probable, the nucellus was free 
from the integument, the space between must have been a very narrow one. 
The nucellus itself is also quite narrow, and in good sections preserves 
a fairly constant width throughout its extent, from the chalazal attachment 
below to the base of the pollen-chamber above. The nucellus shown in 
PL XII, P"ig. 15, has an average thickness of -i mm. In other sections, in 
which the nucellus is less perfectly preserved, the thickness is commonly not 
more than *05 mm., probably owing to the fact that the nucellar epidermis 
is usually destroyed. 
Within the nucellus is a dark-coloured structureless line (PI. XI, 
Fig. 5, m.), which doubtless represents the membrane of a large, solitary 
megaspore. The megaspore membrane is always found contracted away 
from the nucellus, with which it was doubtless originally always in contact. 
Unfortunately, the prothallus and archegonia are never preserved. 
Transverse sections of the body of the seed made at different levels 
exhibit some characteristic differences in the appearance of the nucellus. In 
sections across the lower part of the seed the nucellus frequently possesses 
numerous blunt or pointed outgrowths projecting into the space between it 
and the testa. These processes are often rather irregular in their distribu- 
tion and size, and are well shown in some of the original Williamson slides h 
In sections above the middle of the seed these outgrowths are usually less 
conspicuous, so that this feature is of some value in determining whether 
a single transverse section is cut above or below the middle of the seed. 
With regard to the origin of these processes, we believe that they are 
caused by the contraction of the tissue of the nucellus which lies between 
1 e. g. No. 1460 W. 
