488 Watson.— On the Structure and 
either by projections or depressions on the outer side of the same tissue in 
the same specimen. 
M. Renier’s fourth piece of evidence does not distinguish between the 
two theories. 
It now remains to examine the two structural specimens to which 
M. Renier appeals in support of his theory ; both were described by Professor 
Weiss, and full series of sections of them are in the Manchester Museum. 
The first case is the large stem of L epidodendron fuliginosum type, 
which was described by Weiss as the ‘biserial Halonia \ l This specimen 
is regarded by Kidston as a Ulodendron . 
It is unfortunately decorticated to such an extent that in the neighbour- 
hood of the lateral branches little or none of the secondary cortex is 
preserved, and therefore is not in a condition to show that reduplication of 
the cortex which M. Renier claims to see in it. The inner part of the 
outer cortex is, however, very thick and well preserved, and is directly 
continuous from the trunk into the branch. The middle cortex of the 
trunk is also directly and widely continuous with that of the branch. 
Professor Weiss’s account is, of course, both accurate and complete, 
and renders it unnecessary to discuss the stem further. 
The other case, the Lepidode 7 idron vasculare figured by Weiss and 
Lomax, 2 is slightly different, because the branch, instead of leaving the 
trunk nearly horizontally, inclines strongly upwards. 
Examination of Fig. 3 of this paper, which is a median longitudinal 
section of a precisely similar specimen, will show that there is no contraction 
at the base of the branch, which is in organic connexion with the trunk 
over an area of 5 cm., an amount greatly in excess of the diameter of the 
umbilicus of any known ulodendroid scar. 
The longitudinal section figured in Fig. 3 explains the condition 
observed in Knorria by Solms-Laubach : 3 
‘ In the Knorriae . . . the thinner lateral branch will often impede the 
further growth in thickness of the main stem, and then the base of the side 
branchis seen to be embedded on a lateral groove which forms on the stem. 
Knorria is a condition which really represents an internal cast of the 
outer cortex ; the groove referred to by Solms-Laubach is really only a cast 
of the tongue of outer cortex coming down between the branch and the 
stem. This tongue is clearly shown in Fig. 3, and equally well in a series 
of transverse sections of a similar condition on a smaller scale, in Dr. Scott’s 
collection. 
M. Renier’s suggestion, on p. 50 of his memoir, that Lepidodendron 
1 Trans. Linn. Soc. London, 2nd ser., Bot., vol. vi, pp. 217-35. 
2 F. E. Weiss and J. Lomax, The Stem and Branches of Lepodendron selaginoides. Mem. and 
Proc. Manchester Lit. and Phil. Soc., vol. xlix, Mem. 17, 1905. 
3 Solms-Laubach, Fossil Botany, Oxford, 1891, p. 205. 
