56 
Scott . — On a Palaeozoic Fern , the 
he had strong reasons for believing that Williamson’s type-specimens 
also belonged to Ankyropteris . He sent me photographs of Williamson’s 
section 1824, showing that a petiole of the plant had evident peripheral 
loops I at once consulted the original section, and satisfied myself that 
this is the case. The section has been rephotographed by Mr. Tams, and 
is shown in PI. II, Phot. 16. The petiole in question is a perfectly typical 
one of Z. Grayi , and, as Dr. Bertrand pointed out to me, is identical 
with the petiole of which another section is figured by Williamson (’ 89 , 
PL I, Fig. 4). There is little doubt that this petiole belongs to one of the 
associated stems. 
A glance at Phot. 1 6 will show that the band of small elements form- 
ing the external xyiem (x.e:) of the peripheral loop is perfectly evident, 
especially on the left-hand side. 
The proof that Williamson’s type-specimens of Zygopteris Grayi 
belonged to the genus Ankyropteris , as now defined, is entirely due to 
Dr. P. Bertrand, to whom I am much indebted for calling my attention to 
the critical section. 
The difficulty is greater in the case of the later Williamson specimen. 
The preservation of this specimen) good as it is for most purposes, is such 
as to render it difficult to make out the arrangement of the small external 
tracheides. When I described the structure of this stem in my ‘ Studies in 
Fossil Botany ’, I was inclined to regard these elements simply as proto- 
xylem. On a careful re-examination of all the sections, I have observed 
cases where peripheral loops appeared to be present on the leaf-trace, but 
scarcely any were absolutely decisive, as it was seldom possible to distin- 
guish with certainty between the supposed elements of the external xyiem 
(‘ filament ’) and those of the protoxylem on the one hand or the inner 
phloem on the other. 
The leaf-trace shown in PI. II, Phot. 14, seems, however, fairly conclusive. 
The position of this bundle (/./.) relative to the stele is shown in the general 
sketch, Fig. 15, PI. V. One corner of the trace is obliquely truncated, 
recalling the leaf-traces of the Shore specimen. The truncated end is 
coated by a band of small elements, apparently tracheides (see PL II, 
Phot. 14, x.e., and the slightly diagrammatic drawing of the same in PL IV, 
Fig. 11, x.e.). The appearance is remarkably like that of one of the peri- 
pheral loops of the Shore specimen, though of course less clear (cf. PL I, 
Phot. 8, and PL III, Fig. 1). 
Taking the whole of the evidence into consideration, I feel no doubt 
that Dr. P. Bertrand was right in his interpretation, and that this specimen, 
like the others, has peripheral loops and is therefore an Ankyropteris. As 
we have seen, this conclusion is now established as regards the Shore fossil 
and the type-specimens of Williamson ; I believe it may safely be extended 
to all specimens of the Z. Grayi type. 
