LYGINODENDRON ^ 383 



we are acquainted were adventitious. They are very 

 commonly found in connection with the stem (see Fig. 

 142), where they are inserted indiscriminately on nodes 

 or internodes, and on all sides alike. They are not, 

 however, found on all portions of the stem, and were 

 probably limited to its lower region (see restoration, in 

 Frontispiece). By tracing characteristic specimens, 

 with the structure of " Kaloxylon Hookeri" to their 

 junction with the stem, proof was afforded that this 

 fossil was simply the root of Lyginodendron oldhamium. 

 The mode of connection between the adventitious roots 

 and the stem affords proof that the former were 

 endogenous organs, for the cortical tissues proper to the 

 root can be traced throughout the whole thickness of 

 the cortex of the parent stem. Fig. 142, from a radial 

 section of the stem, shows clearly the connection of its 

 tissues with those of the root. The latter happened to 

 be bent, so as to show its transverse section, which is 

 that of a tetrarch root with the structure of " Kaloxylon." 



4. Habit. — We have already described the principal 

 features in the structure of all the vegetative organs of 

 Lyginodendron oldhamium. We may now attempt a 

 reconstruction of the plant, so as to gain some idea of 

 its habit, before going on to consider the subject of 

 the organs of reproduction. 



The stem must have been a comparatively slender 

 one, of great length compared with its diameter. This 

 appears to be proved by the length of the internodes 

 (about an inch or so), and by the fact that every piece 

 of stem shows, on the average, the traces of ten 

 successive leaves (five traces outside the vascular ring, 



