OF THE FOSSIL PLANTS OF THE COAL-MEASUEES. 
235 
Plate 
centre and to the left of the diagram, and with a section of the wood and 
bark, the latter with the rootlets in situ, on the right. The latter section 
is supposed to have passed directly through the centres of the bases of two 
of the rootlets, and tangentially through the remaining three. 
XXXI. fig. 54. Transverse section of a fragment of bark, apparently of Fiploxylon, 
magnified 16 diameters. Mr. Butterworth. 
„ fig. 55. Radial section of the prosenchymatous portion of a similar specimen 
to fig. 54, magnified 65 diameters. 
,, fig. 56. Tangential section of fig. 55, magnified 65 diameters. 
,, fig. 57. Tangential section of the large cells(A) of fig. 54, magnified 60 diameters. 
„ fig. 58. Cast of the external surface of a Favularici, with cicatrices of cones, 
enlarged 2 diameters. Mr. Nield’s cabinet. 
,, fig. 59. Central axis of a small Lepidodendroid cone, enlarged 2 diameters. 
Received September 3, 1871. 
Supplementary Observations. 
Since reading the preceding memoir I have been seeking further information on some 
portions of the subject which are as yet very obscure, especially in connexion with the 
forms represented by the Diploxylon cycadeoideum of Corda. In his ‘Flora der Vorwelt ’ 
he gives both the generic and specific characters of this plant. The essential features 
of the former are that the plants belonging to the genus have an inner cylinder sur- 
rounding the medulla composed of large scalariform vessels arranged without definite 
order. This is invested by a second cylinder, also consisting of scalariform vessels, but 
of smaller size, arranged in radiating fasciculi, and “ radii s vctsorum liyni interni per- 
cursum.'” In his specific description of D. cycadeoideum he affirms “ Radii medullaris 
nulli ” (toe. cit. pp. 5, 6). In his tab. xi. fig. 1 he represents a radial longitudinal 
section in which three sharply defined vascular bundles, unaccompanied by any other 
tissue, proceed upwards and outwards across a field of vertical, barred vessels, which are 
disposed with rigid straightness and perfect parallelism. I think I shall not be ven- 
turing too far if I doubt the perfect accuracy of this figure. But what is of chief im- 
portance at present is the fact that he believes these vascular bundles to spring from his 
inner or medullary rings of vessels, and not from any part of the outer or ligneous zone, 
and that he discovers no traces of cellular medullary rays in his specimen. 
M. Brongniart, as we have seen, found a very similar general arrangement in his 
Sigillaria elegans, only in this plant the inner or medullary vascular cylinder was inter- 
rupted, at intervals, instead of being a continuous ring. lie also found a profusion of 
what he unhesitatingly affirms to be medullary rays ; but the tissues which composed 
them being destroyed, he cannot speak with confidence as to their histological character. 
Besides these he found traces of larger openings in the woody cylinder ; and he correctly 
surmises that these were passages through which the large foliar vascular bundles, seen 
