Zygopteris Grayi of Williamson . 67 
Boodle (’00) : L. A. Boodle, Comparative Anatomy of the Hymenophyllaceae, Schizaeaceae, and 
Gleicheniaceae. I. On the Anatomy of the Hymenophyllaceae. Ann. of Bot., xiv, p. 456. 
Chambers (’ll) : Helen S. Chambers, The Vestigial Axillary Strands of Trichomcines javanicum , Bl. 
Ann. of Bot., xxv, p. 1037. 
Gordon (’ll) : W. T. Gordon, On the Structure and Affinities of Diplolabis Romeri (Solms). 
Trans. Royal Soc. of Edinburgh, xlvii, Pt. iv (No. 24). 
(ll 2 ) : On the Structure and Affinities of Metaclepsydropsis duplex (Williamson). Ibid. 
xlviii, Pt. i (No. 8). 
Gwynne-Vaughan (’02) : D. T. Gwynne- Vaughan, On an unexplained Point in the Anatomy of 
H elminthostachys zeylanica. Ann. of Bot., xvi, p. 170. 
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P- 45i. 
Renault (’69). B. Renault, Etude du quelques v^getaux silicifies des environs d’Autun. i e Etude 
sur la tige de Zygopteris . Ann. des Sci. Nat., Bot., t. xii, p. 161. 
Scott (’00) : D. H. Scott, Studies in Fossil Botany, 1st ed., p. 277. 
(’08) : Studies in Fossil Botany, 2nd ed., p. 306. 
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(’96) : Nachtragliche Bemerkungen zur ‘ Gattung Tubicaulis , Cotta’. Bot. Zeit., Jahrgang 
liv, p. 27. 
Williamson (’74) : W. C. Williamson, On the Organization of the Fossil Plants of the Coal- 
Measures. Part VI. Ferns. Phil. Trans. Royal Soc., 1874, p. 698, Fig. 51. 
(’89) : On the Organization of the Fossil Plants of the Coal-Measures. Part XV 
Phil. Trans. Royal Soc., 1889, B., p. 155, Figs. 1-5 A. (Read in 1888.) 
EXPLANATION OF PLATES I-V. 
Illustrating Dr. Scott’s paper on Zygopteris ( Ankyropteris ) Grayi. 
The Photographs in Plates I and II often need to be examined with a lens. 
PLATE I. 
(Photographs by Mr. W. Tams.) 
Shore specimen. 
Phots. 1-6. Selections from the transverse series of sections, from below upwards. Phots, i, 2, 
3, 5, and 6 show the stele and surrounding tissues. Phot. 4, on a smaller scale, shows the whole stem. 
Phot. 1. (Reversed, as compared with Phots. 2-6.) The arms of the stele are numbered 1-5, 
following the phyllotaxis in kathodic order. The leaf-trace, l.t. (incomplete), and axillary stele, 
a. s. } are shown in the outer cortex, x 8. Scott Coll., 2511. 
Phot. 2. The arm 5 is spreading out laterally and its internal ray becoming interrupted, x 8. 
Scott Coll., 2512. 
Phot. 3. The end of arm 5 is about to separate as a leaf-trace, x 8. Scott Coll., 2514. 
Phot. 4. Complete section. The leaf-trace 5 has now separated (see Phot. 8). Numerous 
aphlebia-strands are seen in the cortex, x 4. Scott Coll., 2516. 
Phot. 5. The leaf-trace 5 has now entered the cortex, x 8. Scott Coll., 2518. 
Phot. 6. The leaf-trace 5 has passed out further into the cortex and is assuming a stouter form. 
The arm 4 is preparing to detach its leaf-trace, x 8. Scott Coll., 2520. 
Phot. 7. Middle part of stele, showing irregular ring of internal xylem, x.i., with the five internal 
protoxylem rays, x about 30. Scott Coll., 2516. 
Phot. 8. Leaf-trace 5 (see Phot. 4). x.e., peripheral loops formed by the small-celled external 
F 2 
