Scott and Mas ten . — The Structure of Trigonocarpus. 125 
base of the seed within the angles of the sclerotesta (PL XIII, Fig. 20, sa.). 
The sclerotesta is shown at s.t. in the figures and exhibits certain differences 
from that of the ordinary form. The section figured in PI. XIII, Fig. 19, 
is, on the whole, the most median one we have, and shows the characteristic 
‘ coffin-shape 5 of the sclerotesta and of the cavity within it, which is quite 
different from the oval form with a rounded base which is seen in all the 
longitudinal sections of Trigonocarpus Parkinsoni (cp. PI. XII, Fig. 12). 
This section (Fig. 19) is evidently not quite radial at the base of the seed, as 
it misses the chalazal attachment of the nucellus n. The nucellus shows 
a ragged appearance due to a number of irregularly disposed processes 
similar to those described in dealing with the nucellus of Trigonocarpjts 
Parkinsoni (p. 119). The base of the sclerotesta is characteristically flat or 
nearly so, and in this section it has a width, to the outside limit of the 
sclerotesta, of about -6 cm. 
At the base of the seed the sclerotesta is produced at the angles into 
two downwardly pointing processes, p.. /., which appear to be sections 
of a circular ridge surrounding the base of the seed. At the apex the 
section is clearly not radial, as it escapes the micropylar beak altogether. 
Three processes are seen rising from the top of this section, the interpretation 
of which is not without difficulty ; they probably represent some of the 
longitudinal ridges of the sclerotesta as they converge to the base of the 
micropylar beak. 
PI. XIII, Fig. 20, is another obliquely longitudinal section of the same 
seed. The basal part of the seed is evidently cut nearly radially, as the 
chalazal attachment of the nucellus, n ., is shown. In the upper part of the 
seed the pollen-chamber, p.c ., is apparently cut through. The base of this 
section shows the downwardly directed processes of the sclerotesta, 
better developed than in Fig. 19, and we think that these two sections make 
it practically certain that there was a circular ridge around the base of this 
seed, a feature which constitutes one of the most distinctive characters 
of the species. In Fig. 20 these processes ( pp .) evidently extended farther 
downward than is shown in the specimen ; only the proximal part of the 
circular ridge is preserved. 
The upper part of this section (PL XIII, Fig. 20) is not cut in the 
median plane. The three ridges shown, r., r\, r., give rise to an appearance 
as though the apex of the seed was provided with a circular ridge similar to 
the crown of a Stephanospermum. This appearance, however, is probably 
deceptive, and is due to the obliquity of the section, which thus passes 
through three of the ordinary longitudinal ridges of the sclerotesta. Three 
similarly placed ridges are sometimes shown in Trigonocarpus Parkinsoni 
when the seed has been cut obliquely, and the two outermost of these have 
frequently been described as caused by the presence of an annular ridge. 
Truly radial sections of T. Parkinsoni passing through the micropyle show 
