508 Agnes Arber .— On the Structure of the Palaeozoic Seed 
Fig. 6. Obliquely transverse section, passing through the hilum (h.) on one side, and one wing 
(w.) on the other, sc. = sclerotesta ; m.c. = mucilage cells of sarcotesta ; v.bJ = branch vascular 
bundle. U. C. L., S. 67 (Shore), x 22 circa. 
Figs. 7 and 8. Two seeds, or casts, described in Williamson’s manuscript catalogue as 
‘ Possibly a nucleus of some of the Sammaropsid forms of Lesquereux W. 1427 (Little Hutton, 
near Peel, Delph, Lancashire), x 1^ circa. 
Fig. 9. Longitudinal section in the principal plane (or plane of flattening), showing the origin of 
the branch vascular bundles ( v.b.' ) from the main bundle ( v.b .). The wing (w.) is partly preserved on 
the right-hand side. b. = seed base with large secretory cells ; sc. = sclerotesta ; sa. = sarcotesta, 
showing very clearly the division into m.c. — mucilage cells, and i.c. = smaller inner cells. U. C. L., 
S. 65 (Shore), x 20 circa. 
Fig. 10. Transverse section close to the base. On the right the section passes through a sinus 
(sin.), but on the left, as it is somewhat oblique, it dips into the sclerotesta (sc.) below the sinus. 
On the right the branch bundle (v.b/) is seen passing off from the main bundle, on the left the 
branch bundle (v.b.') is cut further out. r = median ridge of sclerotesta. U. C. L., S. 43 (Hough 
Hill, Stalybridge). x 26 circa. 
PLATE XXXVIII. 
Drawings. 
Fig. 11. One end of a transverse section, showing the junction of the two valves of the sclerotesta 
(j£.) and base of the sarcotestal wing (vu.). The vascular elements (xy.) form a row down the middle 
of the wing. The large outer cells of the sarcotesta (m. c.) are poorly preserved, i. c. = inner cells of 
sarcotesta; n. and m. — nucellus and megaspore. U. C. L., S. 46 (Shore), x 90. 
Fig. 12. Slightly oblique transverse section of part of sarcotestal wing. m. c. = mucilage cells. 
U. C. L., S. 57 (Hough Hill), x 90. 
Fig. 13. Edge of a transverse section through sclerotesta (sc.) and sarcotesta (sa.), showing inner 
cells of sarcotesta (i.c.), mucilage cells (m. c.), and small outermost cells (o.c.). U. C.L., S. 51 
(Dulesgate). x 150. 
Fig. 14. Transverse section of sclerotesta (sc.) and sarcotesta (sa.) to show the proportion which 
the size of the unswollen mucilage cells (m. c.) bears to the thickness of the sclerotesta. U. C. L., 
S. 51 (Dulesgate). x 28. 
Fig. 15. Transverse section of sclerotesta (sc.) and sarcotesta (sa.) to show the relative size to 
which the mucilage cells (ni. c.) may attain in extreme cases (cf. Fig. 14). U. C. L., S. 50 (Shore). 
X 28. 
Fig. 16. Small part of a slightly oblique longitudinal section, showing the edge of the sclerotesta 
(sc.) and the sarcotesta (sa.). i. c. — small inner cells of sarcotesta; m. c. = mucilage cells ; 0. c. = 
membrane probably representing the remains of the small outer cells of the sarcotesta. Wat., A. 113 
(Dulesgate). x 155. 
Fig. 17. Transverse section of sclerotesta (sc.) and nucellus (n.), probably from near the top of 
a seed. Wat., A. 248 (Shore), x 28. 
Fig. 18. Nucellus from Fig. 17 enlarged. Possibly the section passes through the rather flat roof 
of the pollen-chamber. Wat., A 248 (Shore), x 387. 
Fig. 19. Transverse section of a contracted and carbonized nucellus, probably near its apex, to 
show the four-angled form. D. H. S. 2259 (Shore), x 42. 
Fig. 20. Tracheides of branch vascular bundle from transverse section of seed, showing flattening 
and extension in the principal plane. [The position of the bundle can be understood by reference to 
Text-fig. 2, c.] D. H. S. 2428 (Shore), x 375. 
Fig. 21. Apex of nucellus in longitudinal section, showing obliquely cut pollen-chamber (?). 
U. C. L., S. 47 (Shore), x 46. 
Fig. 22. Longitudinal section of a small part of the nucellus, from a section in which it is 
unusually well-preserved, showing nucellar epidermis (n.e.), thin-walled nucellar tissue (n.c.), and 
nucellar tapetum (tap.). U. C. L., S. 36 (Shore), x 155. 
Fig. 23. Nucellar epidermis (n. e.) (or possibly nucellar tapetum) enclosing megaspore 
membrane (m.) (or possibly carbonized tapetum), from a transverse section. D. H. S. 2428 
(Shore), x 90. 
