Fig. 15. 
Fig. 16. 
i pes 
Fig. 18. 
Fig. 19. 
Fig. 20. 
Fig. 21. 
PROF. F. W. OLIVER ON THE STRUCTURE 
. Apex of pollen-chamber and group of pollen-grains represented in fig. 2. p., grain with 
internal cells in surface view ; mp, longitudinal oblique section of a grain showing 
* replum ” ; p.’, transverse section of a grain showing internal walls—this grain is drawn 
in Pl. 43. figs. 30 & 31; ni, grain in longitudinal section showing replum, drawn in 
Pl. 44. fig. 35; p. and p. also shown enlarged in fig. 16; co., collar. x58. S74. 
(See p. 376.) 
Apex of nucellus in longitudinal section. Resting on the apex is the collar (co.). In 
the pollen-chamber a large pollen-grain with internal cells showing and a papilla on its 
 underside ; three abortive foreign pollen-grains are also present. x 16. Williamson 
Collection 1486 a. (See p. 378.) 
The two right-hand pollen-grains of figs. 2 and 14, much enlarged. nl, in transverse 
section, showing the internal walls; ez., exospore: this grain is represented in PI, 48. 
figs. 30 & 31. př, in longitudinal section, showing replum within: this grain is 
represented in Pl. 44. fig. 35. x100. S7a. (See p. 376.) 
Stephanospermum caryoides, n. sp. 
Almost median longitudinal section of the seed. The black sclerotesta is in contact with the 
matrix. The micropyle, funnel-shaped, is seen at the summit. The nucellus is remote from 
the sclerotesta, except at the base, the space being somewhat increased, but not very much, 
owing to the three fissures in the preparation. "The pollen-chamber is very broad, with well- 
preserved shoulder-tissue at the sides. The large embryo-sac contains the prothallium in 
its upper half. On the left-hand side of the embryo-sac the double membrane has resulted 
from the epithelium of the sclerotesta having separated from: the latter till it touches the 
nucellar wall just where this is fractured. At f the dark fragments represent a portion of the 
macrospore-wall and overlying tracheal sheath that have become detached from their position 
and carried into the embryo-sac. This happened prior to mineralisation. æ indicates the 
apex of the nucellus. In the matrix to the left is a Cordaitean bud. x 3. S'la. (See 
p. 374.) 
Part of pollen-chamber and shoulder from the same specimen. Lying at the side of the 
pollen-chamber is an intact pollen-grain (p. and a pair of internal cells from another 
grain (p.). s., septum, i. e. lower limit of pollen-chamber, below which is the narrow supra- 
archegonial gap. On the right the macrospore is broken through (cf. fig. 17). x 20. 
S'la. (See p. 375.) 
A pair of tracheides from the tracheal mantle. Their average diameter is about 27». X 169. 
S'la. (See p. 375.) 
Secondary cell-reticulum contained in the cell 4 of Pl. 44. fig. 42. x250. S'la. (Seep. 381.) 
PLATE 43. 
Stephanospermum akenioides, Brongniart. 
Median longitudinal section through a portion of the base of the seed shown in fig.7. The 
entering vascular bundle (e A", tracheal disc (¢.d.), and tracheal mantle (/.m.) are found in 
continuity. The bundle is accompanied by a layer of parenchyma (sh.), which expands 
below the tracheal disc into the parenchymatous layer (p ), which is continued as the crushed 
hypoderm of the nucellus. Below the parenchyma is a plate of sclerised cells with car- 
bonaceous contents (sci).  Distally, this plate is attached to the angle of confluence of the 
