SPECIMENS OF FOSSIL WOODS IN NATAL MUSEUM, 379 



niinous matter has partially filled the medullarv cells. The walls are 

 partially silicified. while those of the fibre marked d.f. are more com- 

 pletely so. 



Fio. 18.— X 150. Mus. No. 284. Port Durnford. Zululand. 

 Longitudinal tangential section in the condition described under fig. 

 12. The outlines of the wood fibres have mostly disappeared. 



Fig. 19. — x loO. Mus. No. 234. Longitudinal tangential section 

 at about the same stage of change as seen in fig. 12. The bituminous 

 matter at first confined to the cavities of the wood fibres has now 

 extended into elongated flakes or chains. In one of the mediiUary rays 

 the remains of a gland (resin-gland ?) can be seen. 



Fig. 20.— x 150. Mus. No. 234. Port Diu-nford. A small piece 

 of a longitudinal tangential section in the condition of fig. 19. 



Fig. 21.— X 150. Mus. No. 234. Port Durnford. Longitudinal 

 tangential section in miich the same condition as in fig. 13. The 

 bituminous sul)stance is becoming dispersed in the general matrix (;».) 

 which is being transformed, but the remains of medullary rays can 

 be seen. 



Fig. 22. — x 150. Mus. No. 232. Liyazan. Longitudinal tangential 

 section in same condition as in fig. 14. i-jn.r. i-epresents the remnant 

 of a medullary ray. A vertical striation is l)eginning to be visible. 



Fig. 23a.— X lOO. Mus. No. 228. "Wood Bed." False Bay. 

 Longitudinal tangential section of jet-like substance (cf. fig. 15) 

 exhibiting a vertical striation, the i-emains of medullary rays (r. »».»•.) 

 and mici'oscopic cracks (m.c.) and lenticular cavities (I.e.). 



Fig. 23b. — The same viewed with crossed prisms. A succession of 

 short horizontal dark and light areas becomes conspicuous. 



Fig. 24. -X 100. Mus. No. 228. "Wood Bed," False Bay. 

 A somewhat radial section exhibiting medullary rays ; the lowest {m.r.^) 

 is not completely transformed. The i-emnant of a vessel (r.) can be 

 seen. 



Fig. 25.— X lOo. The same viewed with crossed prisms exhibits a 

 succession of long, more or less horizontal, dark and light areas ; also 

 patches showing a coarse cross-hatched structnre. Towards the bottom 

 there is an indication of a horizontal microscopic fracture (ni.f.) which 

 is bordered Ijy homogeneous matei-ial. 



Fig. 26 a.— X 150. PI. XXV. Mus. No. 228, T. •' Wood Bed," False 

 Bay. Jet-like subst.ince in longitudinal tangential section in which 

 the medullary rays have not been wholly obliterated and transformed. 



Fig. 2f)B. — The same viewed with crossed prisms shows on tlie 

 right-hand side cellular elements in the midst of the jet-like substance. 

 The specimen has undergone some disintegration, and lens-shaped 



