Seward. — On the genus Myeloxylon ( Brong .). 5 
fragments there are certain characters which suggest the 
possibility that they ought not to be included in the same 
genus as those described by Renault and others, or as the 
fragments which I have figured. In Williamson’s specimens 
there are peculiarities in the structure of the bundles, and in 
the arrangement of the hypodermal tissues, which distinguish 
them from other described examples of Myeloxylon : at the 
same time there are several points of resemblance. The 
spaces in the bundles, originally described by Williamson as 
gum-canals and shrinkage-cavities, are now recognised by 
him as ‘ true phloem-portions of the fibro-vascular bundles V 
Myeloxylon is classed by him with the Ferns, and the 
points of agreement with the Marattiaceae are considered at 
some length. Some specimens, which Prof. Williamson has 
generously lent to me for examination, may, I hope, throw 
further light upon the botanical position of those to which I 
have briefly alluded. 
Grand’ Eury 2 has figured what he considers to be a piece of 
the epidermis of Myeloxylon , showing a number of stomata. 
He points out a general resemblance between this genus and 
Angiopteris as regards the arrangement of the vascular 
bundles, but recognises a difference in the shape of the in- 
dividual bundles ; in Angiopteris they are elongated con- 
centrically, in Myeloxylon they are either circular or elongated 
radially. 
We come next to an important paper by Schenk 3 , pub- 
lished in 1882. An examination of Cotta’s original specimens 
in Berlin led Schenk to the conclusion that Myeloxylon re- 
sembles Cycadean petioles more closely than the petioles 
of Marattiaceae. In this paper we find the collateral nature of 
the bundles insisted upon as a strong argument in favour of 
Cycadean affinities : many other characters, whose importance 
had not been previously recognised, are dealt with in detail. 
1 Letter from Prof. Williamson, June, 1890. 
2 Flore Carbonifere du departement de la Loire et du centre de la France 
(Mem. pres, par divers savants a l’Acad. des Sci. de l’Instit. de France, vol. XXIV. 
1877. PI. XIII. Fig. 7). 
3 Schenk, Ueber Medullosa elegans (Engler, Bot. Jahrb., vol. III. p. 156, 1882). 
