On a Palaeozoic Fern, the Zygopteris Grayi 
of Williamson. 
BY 
D. H. SCOTT, F.R.S., P.L.S. 
With Plates I-V and one Figure in the Text. 
Introduction. 
HE species Zygopteris Grayi was founded by Williamson in 1888 
1 - (Williamson, ’ 89 ) on some specimens in a nodule from Oldham, which, 
though imperfectly preserved, enabled him to recognize the chief points in 
the morphology of the plant. Williamson had previously recorded a stem 
of the same type under the name of Anachoropteris Decaisnii , Renault 
(Williamson, ’ 74 , p. 699). 
A much better specimen than any of those described by Williamson 
was found later by Mr. J. Lomax, who was also the discoverer of the type- 
specimens. Five sections of this stem are in Williamson’s collection, but 
his intention of figuring it was never carried out. 1 Figures have since been 
published by myself (Scott, ’ 00 , Figs. 97, 98 2 ), Dr. P. Bertrand (’ 09 , PI. XI, 
Fig. 78), and Dr. Kidston (’ 10 , Figs. 1-4), but the specimen has never been 
fully illustrated. 
In 1910 I received from Mr. Lomax a series of sections of a new 
specimen from a fresh locality — Shore, Littleborough, so well known for 
other interesting fossils with their structure preserved. The present paper 
is based primarily on the new specimen, with comparative references to the 
others and especially to the best Williamson specimen mentioned above. 
The question whether all known specimens can really be referred to the one 
species, Z. Grayi> will be discussed in the latter part of the paper. 
It will be well to preface the detailed observations with a short 
summary of what is already known of the structure of the Zygopteris Grayi 
type. 
1 I know of eight sections (all transverse) of this specimen, namely 1818 A and i9i9Atoi9i9D 
in the Williamson Collection (see p. 66), 308 in that of Dr. Kidston, R. 443 in the Manchester 
Museum Collection, and 184 in my own. The proper order of these sections will be given below 
(p. 52). The sections of the type-specimens in the Williamson Collection are: 1817-1843 (excl. 
1818 A) and 1919. 
2 Figs. 115, 1 16 in the second edition, Scott, ’08. 
[Annals of Botany, Vol. XXVI. No. Cl. January, 1913. 
