HICK : SOME RECENT ADVANCES IN BRITISH PAL.EOBOTANY. 51 
is known, our knowledge has been greatly extended by the recent 
investigations of Williamson and Scott, The details of these are 
contained in the memoir referred to already, and a study of them 
will show how much they are in advance of the knowledge previously 
acquired. 
On the affinities of Sphenophyllum, with regard to whieh different 
authorities hold different views, the researches referred to throw little 
or no new light. They confirm, however, the conclusion that in the 
Sphe7iophyllece we have a group which cannot be classed with any of 
the existing types of Vascular Cryptogams, but they still leave open 
the question as to where their nearest allies are to be looked for. 
Kaloxylon Hookeri, Will. 
Among Carboniferous plants with structure, there are few or 
none whose sections present a more striking appearance than those 
placed in the genus Kaloxylon. The genus was instituted by 
Williamson in 1876, to receive a number of specimens which he 
described under the name of Kaloxylon Hookeri,^' and which he treated 
as fragments of stems or branches. Further specimens in different 
stages of development were described and figured by him in 1887,t 
and it was then suggested that the least developed specimens were 
probably rootlets, but the older specimens were still treated as stems. 
Some years later, Williamson made a re-investigation of the 
structure of Lyginodendron in association with Dr. D. H. Scott, and 
in the course of the w^ork the important discovery was made that 
Kaloxylon is the adventitious root of Lyginodendron, and not an 
independent plant at all. In 1894 they communicated a joint paper 
to the Royal Society,| from which it appears that they had succeeded 
in finding " specimens, presenting in every respect the typical 
Kaloxylon structure," " in actual continuity with the stem of 
Lyginodendron,'' and arising from it in such a way as, taken with 
the anatomical structure, proved that they were roots. 
In ignorance of all this, I was myself investigating the structure 
of Kaloxylon Hookeri, as shown in a number of fine preparations by 
* Phil. Trans., 1876. f Phil. Trans., 1887. 
i Proceedings, vol. 56. 
