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Kisch . — The Periderm of Fossil Lycopo diales. 
EXPLANATION OF PLATE XXIV. 
Illustrating Miss Kisch’s paper on the Periderm of Fossil Lycopodiales. 
(Photographs by Mr. F. Pittock, Zoological Department, University College.) 
Fig. i. Transverse section of the periderm of Stigmaria, type i, showing the delicate cells on 
the inner margin, and at x a cell which has just divided. The short files in the periderm are well 
seen, and the primary cortex on both sides is preserved. U. C. L. Coll., D 8. x 45. 
Fig. 2. Transverse section of the periderm of Stigmaria, type 2, showing the irregular, wide- 
celled outer portion, a, the smaller-celled internal portion, b, which is broken off towards the 
interior, the supposed line of the phellogen, ph , and the divisions in the cells of the outer cortex as 
at c. U. C. L. Coll., D 8. x 45. 
Fig. 3. Colour zones in the periderm of Lepidodendron Scottii caused by differences in the 
preservation of the cells. U. C.L. Coll., A 41. x 35. 
Fig. 4. Zones in the periderm of Sigillaria scutellata caused by the smaller size of a few layers 
of cells. U. C. L. Coll., Bn. x 35. 
In all cases the peripheral edge of the section is placed uppermost on the plate. 
