66 
Scott. — On a Palaeozoic Fern , the 
The photographic illustrations are for the most part the work of 
Mr. W. Tams, but some were taken for me long ago by my friend Mr. L. A. 
Boodle. 
The drawings reproduced in Plates III to V are partly by Mr. G. T. 
Gwilliam, partly by Miss G. C. Harrison. 
To all these collaborators I am greatly obliged for their aid. 
APPENDIX. 
It may be of interest to reproduce Williamson’s MS. description of the sections 
of his later, unpublished specimen. The original notes are accompanied by rough 
sketches to which the letters refer. I am indebted to Dr. F. A. Bather, F.R.S., for 
a copy of this passage, from the Williamson Catalogue, preserved in the British Museum 
(Natural History) : 
‘j8i8a. R[achiopteris'] Grayii. The most perfect section yet obtained. To be 
figured. Oldham. Lomax. 
1919 a. Rack. Grayii. Trans. Section of a second specimen free from the 
abnormal mineralization of the specimens previously described. Structure of its 
secondary branches distinct. Oldham. Lomax. 
1919 b. Rack. Grayii. Trans. A second section of 1919 a, showing some 
marked features. The extremity of each of the five radii on the transverse section 
of the axial bundles is square, a. In another radius this square end is detached, b ; in 
another ray this latter section seems to have divided into two, the “ Axilspross ”, c, 
and the Zygopteroid petiole, d. It is thus evident that these two structures spring 
from the main vascular axis of the stem as a single bundle, a and b , but that they 
divide as they ascend into c and d. Stenzel says it is so with his Zygopteris scandens , 
but he thinks that the primary bundle is a Zygopteroid one from which the “ Axil- 
spross ” is a secondary branch. This is not the case in my specimen. He also 
thinks that the “Axilspross” is an abortive bud. I doubt this. Oldham. Lomax. 
1919 c. Rachiopteris Grayii. Trans. A third section of the same with one 
secondary branch entirely free and a second one just separating from the central axis. 
Oldham. Lomax. 
1919 d. Rachiopteris Grayii. Trans. A fourth section from the above 
specimen. Lomax/ 
References. 
Benson (’ll) : Margaret Benson, New Observations on Botryopteris antiqua, Kidston. Ann. of 
Bot., xxv, p. 1045. 
P. Bertrand (’ 08 ) : Paul Bertrand, Sur les stipes de C lepsydropsis . Comptes Rendus, Nov. 16, 
1908. 
: — 1 (’ 09 ) : Etudes sur la fronde des Zygopterid^es. Lille. 
(’ll) : Structure des stipes d ' Asterochlaena laxa , Stenzel. Mem. de la Soc. 
G^ologique du Nord, t. vii. I. 
