Kaloxylon Hookeri and Lyginodendron Oldhamium. 115 



the stem, to which Kaloxylon Hookeri served as a root, among 

 those stems in which there is a preponderance of the same 

 kind of tracheae. Among such stems those referred to the 

 genera Heterangium and Lyginodendron are the most con- 

 spicuous, and as it happens they are not infrequently found 

 in the same localities as Kaloxylon Hookeri. As a first 

 approximation, then, we may say that Kaloxylon Hookeri 

 may possibly be the root of either Heterangium or Lygino- 

 dendron. 



A still closer examination and comparison of the 

 various tissues met with in these three genera of fossil 

 plants enables us, however, to go much further than this. 

 For it shows that the cortex of Lyginodendron Oldhamium, 

 is characterised by an inner parenchyma which is identical 

 with the corresponding tissue of Kaloxylon Hookeri. It has 

 been pointed out that in the cortex of all the three types 

 of the latter plant, we have a thin-walled parenchyma, in 

 which are scattered, singly or in small groups, elongated 

 canals or cells containing some black substance. This 

 structure gives quite a special character to this plant and 

 enables us to recognise it and even fragments of it, without 

 any difficulty, among the multitude of other plants 

 associated with it. Now, in well-preserved specimens of 

 Lyginodendron Oldhamium the inner zone of the cortex is 

 composed of an identical thin walled parenchyma in which 

 are exactly similar elements with black contents, scattered 

 singly or in small groups in the same manner as in 

 Kaloxylon Hookeri. The whole tissue is so peculiar to, and 

 characteristic of, this Kaloxylon, that its presence in 

 Lyginodendron Oldhamium seems sufficient, when combined 

 with the identity of their vascular elements, to warrant 

 the conclusion that the latter, and Kaloxylon Hookeri, 

 are the stem and the root of one and the same plant. The 

 fact that in the hypoderma of the former we have a charac- 

 teristic stereom which is absent from the latter, is nc 



