Mesoxylon Lomaxii and M. poroxyloides . 1029 
Solms-Laubach, (’ 96 ) : Count Solms-Laubach, Ueber die seinerzeit von Unger beschriebenen 
strukturbietenden Pflanzenreste, &c. Abh. d. K. Preuss. Geol. Landesanstalt, neue 
Folge, Heft 23, Berlin, 1896. 
Weber and Sterzel (’ 96 ) : O. Weber und J. T. Sterzel, Beitrage zur Kenntnis der Medulloseae. 
Ber. d. naturvviss. Gesellsch. zu Chemnitz, xiii, 1896. 
Zalessky (’ 09 ) : M. D. Zalessky, Communication preliminaire sur un nouveau Dadoxylon a fais- 
ceaux de bois primaire autour de la moelle, &c. Bull, de l’Acad. Imp. des Sci. de 
Saint-Petersbourg, 1909, p. 1175. 
(’ll 1 ) Etude sur Panatomie du Dadoxylon Tchihatcheffi , Goppert, sp. Mem. du Comite 
Geol., nouvelle serie, livr. 68, Saint-Petersbourg, 1911. 
(’ll 2 ): Etudes Pal^obotaniques, i re partie, p. 13. Note preliminaire sur le Caenoxylon 
Scotli , nov. gen. et sp., 1911. 
DESCRIPTION OF PLATES LXXXVII-XC. 
Illustrating Dr. Scott’s paper on Mesoxylon. 
The photographic figures require to be examined with a lens. 
PLATE LXXXVII. 
Mesoxylon Lomaxii. 
Photographs by Mr. W. Tams. 
Fig. 1. General transverse section of the stem, showing the patchy preservation characteristic of 
roof-nodule specimens, x nearly 2. Slide 2328. 
Fig. 2. Half of another transverse section, better preserved, d , Dictyoxylon zone ; pd , peri- 
derm. x about 3. Slide 2325. 
Fig. 3. Tangential section from inner part of wood, showing the twin-bundles of a leaf-trace 
(/./.) and their junction below, x 10. Slide 2380. 
Fig. 4. Somewhat oblique section, showing the converging twin-bundles of a leaf-trace (/.A). 
sk, bundle-sheath; /., pith, x about 30. Slide 2325. 
Fig. 5. Leaf-trace in the act of fusion, x, centripetal xylem ; sh } bundle-sheath ; p, pith, 
x about 40. Slide 2328. 
Fig. 6. Double leaf-trace in the phloem : bundles slightly displaced, x, centripetal xylem of 
a bundle ; x 2 , secondary wood of stele ; pd, periderm ; the dark bodies are the ‘ secretory sacs \ 
x about 45. Slide 2325. 
Fig. 7. Quadruple leaf-trace in the inner cortex, x, centripetal xylem of a bundle, x about 
45. Slide 2325. 
PLATE LXXXVIII. 
Mesoxylon poroxyloides. 
Photographs by Mr. W. Tams. 
Fig. 8. General transverse section, d.s., displaced segment of stem, which has slipped from 
a different level ; d } Dictyoxylon cortex, x 3-2. Slide 2352. 
Fig. 9. Twin-bundles of a leaf-trace converging on approaching pith, x, centripetal xylem of 
bundles ; sh, imperfectly developed sheath ; p , outer zone of pith, here alone preserved, x about 
40. Slide 2352. 
Fig. 10. Double leaf-trace, just fused, at margin of pith, x, centripetal xylem; inner, p" , 
outer zone of pith, x about 40. Slide 2352. 
Fig. 11. Approximately tangential section through the twin-bundles of a leaf-trace reaching 
the pith. The plane of section passes gradually inwards towards the bottom. Id., leaf-trace; 
p , outer zone of pith, x about 30. Slide 2358. 
