1 1 6 Scott and Mas ten , — The Structure of Trigonocarpus. 
collection 1 has a micropylar beak almost 3 cm. in length, or quite double 
that of the body of the seed. As will be pointed out later in this paper it 
is quite possible that more than one species of Trigonocarpus is represented 
among these casts, and some forms may have had a longer micropylar beak 
than others. 
The series of transverse sections cut at successively higher levels, shown 
in PL XI, Figs. 6-8, and PI. XII, Figs. 9-1 1, will serve to illustrate the 
changes which take place in the micropylar region of this seed. Figs. 6, 8- 
10 are magnified about six times, Fig. 7 about six and a half, and Fig. 11 
about thirty-two times. The sections from which P'igs. 9-1 1 were made 
are among those which were described by Mr. Wild in the paper previously 
referred to 2 . The changes which take place in the degree of prominence 
of the principal and secondary longitudinal ridges of the sclerotesta as they 
are traced from the body of the seed into the micropylar beak have already 
been described (p. T07), and are illustrated in Figs. 6-8. 
PI. XI, Fig. 6 , is a transverse section across the upper part of the body 
of the seed, and probably passes through the walls of the pollen-chamber 
seen at/. The central cavity of the seed is beginning to assume a triangular 
outline, showing that the section is cut quite close to the base of the micropyle. 
The sclerotesta, sJ., and sarcotesta, sa. y are fairly well preserved, and 
the former shows the usual splitting along the principal ridges. The outer, 
lacunar part of the sarcotesta is destroyed, with the exception of the limiting 
layers, /., which can be traced round the greater part of the seed. In some 
places the limiting layers of the sarcotesta have been so pressed in as to be 
in contact with the sclerotestal ridges, so that the rest of the sarcotesta in 
these places has been totally destroyed. There seems no reason to suppose 
that the transverse section of the complete seed at this level was other than 
circular. 
PL XI, Fig. 7, shows a transverse section cut at a somewhat higher 
level. It evidently traverses the lower thicker part of the micropylar 
beak. The micropylar canal, t.m. y has now acquired its characteristic 
triangular form, and in one place the sclerotesta, s.t shows splitting in 
a position corresponding to one of the principal ridges of the body of the 
seed. The limiting layers, /., of the sarcotesta can be traced the whole dis- 
tance round the seed, although in places they have evidently been much 
disturbed, as is shown by the overlap on the right side. The sarcotesta has 
the form of two wings, one on either side of the boss formed of the central 
sclerotic tissue. The total spread of the £ wings ’ in this slide is about 
19 mm., or, allowing for the overlap of about 3-5 mm. on the shorter (right) 
side, this would make the two sides roughly equal and the total spread 
of the ‘wings’ about 21 mm. The width of one side of the triangular 
micropyle is nearly 2 mm. 
1 Figured in Scott (’05) (1), Fig. 33, p. 146, 
2 Wild (’00), 
