Zygopteris Grayi of Williamson . 69 
Fig. 6. Aphlebia-strand, v.b., in the outer cortex. The strand is much extended tangentially, 
x 40. Scott Coll., 2516. 
PLATE IV. 
Fig. 9 by Miss G. C. Harrison ; the others by Mr. G. T. G william. Figs. 7-10, Shore specimen. 
Fig. 7. Aphlebia detached from cortex of stem, c. v.b., one of the vascular bundles of the 
aphlebia ; the other is only indicated by a gap in the tissue ; h., multicellular hairs of the stem, 
x 30. Scott Coll., 2516. 
Fig. 8. Somewhat diagrammatic longitudinal section of stem. The cross-hatched area is the 
outer cortex, st., stele, cut rather obliquely so that the 1 mixed pith ’ is seen below, and two of 
the internal rays, passing out from it, above, aph., aphlebia-strand, passing out through the cortex, 
x 5. Scott Coll., 2525. 
Fig. 9. Transverse section of an axillary stele (the same as shown in Phot. 1, but two sections 
higher up), x.i ., internal xylem ; p., parenchyma of the e mixed pith ’ ; x., large-celled xylem-zone ; 
c. y part of cortex ; -> S., direction of main stele of stem, x 44. Scott Coll., 2513. 
Fig. 10. Longitudinal section of another axillary stele, passing through the ‘ mixed pith’. 
x.i., internal xylem ; px., protoxylem, consisting of spiral tracheides ; the parenchyma of the 
‘ mixed pith ’ is shown above ; x, large-celled xylem-zone. x 70. Scott Coll., 2527. 
Figs. 11, 1 2. Williamson’s later specimen. 
Fig. 11. Undivided leaf-trace in the outer cortex, the same as shown in PI. II, Phot. 14, and 
in the diagram PI. V, Fig. 15, l.t. x.e., small-celled external xylem of a peripheral loop, 
x about 50. Scott Coll., 184. 
Fig. 12. Undivided leaf-trace on the border of the inner and outer cortex. From section 
figured in Scott, ’ 08 , Fig. 115. A zone of inner cortex surrounds the trace, x.i., internal xylem ; 
x., outer xylem-zone ; ph ., phloem with large sieve-tubes, x 28. Williamson Coll., 1919 A. 
PLATE V. 
Figures by Mr. G. T. Gwilliam, from Williamson’s later specimen. 
Fig. 13. Foliar bundle, L.T. , and axillary stele, A.S., just separated, with inner and outer 
cortex between them ; whole section shown in PI. II, Phot. 12. x., x., large-celled xylem of bundle 
and axillary stele ; ph., ph., phloem of bundle and stele ; x.i., internal xylem of stele, x 28. 
Williamson Coll., 1919 B. 
Fig. 14. Arm of stele, st., in transverse section, giving off laterally the stele of a root, rt . ; 
c., inner cortex, x about 40. Manchester Coll., R. 443. 
Fig. 15. Diagram of transverse section, showing relative positions of the stele, st . ; an undivided 
leaf- trace, l.t. (shown in PI. II, Phot. 14, and Plate IV, Fig. 11) ; a foliar bundle, f.b., and its 
axillary stele, a.s. The gap in the cortex was filled by a Stigmarian rootlet, x 6. Scott Coll., 184. 
