OF THE BRITISH COAL MEASURES. 105 
Figs. 8-12. Heterangium tilieoides. 
Fig. 8. Transverse section of stem from specimen 3, showing two leaf-traces. 
v.b.', inner trace consisting of two bundles etaitiha. from stele; »0.2, outer trace, 
consisting of two bundles in the pericycle, each SS signs of division ; 
pc., pericycle ; e., portions of cortex. 
x 9. Slide, Univ. Coll., N. 12. 
Fig. 9. Part of stem from the same series, higher.up, showing the outer trace (v.2.), now in 
the cortex, and consisting of two double bundles. 
X., primary, x.?, secondary xylem of stele ; ph., phloem; pe., pericycle; c., cortex. 
x 12. Slide, Manchester, Q. 58. 
PLATE 4, 
Fig. 10. Detached petiole, containing four distinct bundles. s.p., sclerotic plates. 
x 18. Slide W. 1694, 
Fig. 11. Transverse section of adventitious root, tetrarch or possibly pentarch, with secondary 
wood ; outer cortex probably missing, 
x 30. Slide, Univ. Coll., N. 12. 
ES 12. Part of young stem, from specimen 4, showing a double leaf-trace. 
v., primary, v., secondary xylem of stele; ph., phloem; pe., pericycle in which the 
two a of the leaf-trace are embedded. Cf. Pl. 1. Phot. 8. 
x 18. Slide S. 1323. 
Figs. 13-18. Heterangium Lomavii. 
Fig. 13. Form 8. ‘Transverse section of stem, specimen 2, showing stele with a small 
amount of secondary wood, pericyele, and cortex. 
V.b., v.b., the two bundles of the leaf-trace; the two protrusions of the wood between 
them are connected with the bases of adventitious roots. 
x 15. Slide S. 445. 
Fig. 14. Form 8. Part of the xylem in radial section, passing through a peripheral strand. 
Ppt., protoxylem ; æ., primary, .”, secondary xylem-elements. 
x 183. Slide W. 1915. R. 
Fig. 15. Ferm 8. Part of the cortex in radial section, showing the Sparganum hypoderma 
on the outside, three sclerotic masses in the inner cortex, and pericycle below. 
x 20. Slide, Manchester, R. 638. 
Fig. 16, Form g, specimen 2. Transverse section of stem, showing the crushed stele, with 
a possible double leaf-trace (v.b.), pericycle, Sd cortex; in the latter the large 
and numerous sclerotic masses are conspicuous. 
x 10. Slide S. 936. 
Fig. 17. Form g, specimen 2a. Transverse section of a smaller stem. A double leaf-trace 
is passing out. 
v.b., one of the two strands in the outer cortex ; v./.!, the other strand displaced. 
x 15. Slide S. 2306. 
Fig. 18. Detached petiole, transverse. 
v.b., the four bundles of the petiole ; r., an intrusive root of the “ Kaloxylon” type. 
x 90. Slide S. 236. 
Hed minimum. 
Fig. 19. Transverse section of stem. 
v.b., leaf-trace beginning to divide. 
x32, Slide S. 1813. 
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