A Fossil Solenostelic Fern. 
BY 
E. M. KERSHAW, M.Sc. 
Assistant-Lecturer in Botany in the Victoria University, Manchester. 
With Plate LVIII and a Figure in the Text. 
A MONG the flora represented in the mineral nodules recently collected 
by Dr. Marie Stopes from the Cretaceous of Japan, is a fragment of 
a fern stem which is particularly interesting, since the anatomy shows it to 
be of the solenostelic type, and hence it seems of sufficient interest to merit 
description in detail. At present the only recorded example of a fossil 
fern with this structure is Psaronius Renaitlti , 1 which seems essentially 
solenostelic, although in the sections at present known the stele is not com¬ 
pletely closed at any one level; 2 thus there is still the possibility that 
P. Renaulti may be a simple dictyostelic stem. 
The Japanese stem, although only about 3 cm. long, fortunately 
includes a node, and shows the departure of a lateral branch with its re¬ 
lation to the leaf-trace. The preservation of the tissues is in parts extremely 
good, and the structural details can clearly be seen. Although the fossil 
shows marked resemblances to some of the living groups of ferns, there is 
not sufficient evidence to identify it with or include it in any of these groups ; 
therefore it seems necessary to form a new genus which might temporarily 
be used for this and any other such fragmentary portions of fossil soleno¬ 
stelic ferns that may be discovered, and do not show sufficient resemblance 
to living forms to justify inclusion with them. I therefore suggest the name 
Solenostelopteris for the genus. The species name japonica is given to this 
specimen, as it comes from the Japanese deposits. 
Description of the Stem. 
The fragment of the stem was from 3 to 3-5 cm. long, and from this 
nine transverse sections were prepared. 
The Text-fig. shows the general shape of the solenostele in the various 
sections. 
1 Scott, D. H. (’ 08 ), Studies in Fossil Botany, 2nd ed., vol. i, p. 301. 
2 I am indebted to Dr. Scott for this information. 
[Annals of Botany, Vol. XXIV. No. XCVI. October, 1910.] 
