72 DR. D. H. SCOTT ON THE HETERANGIUMS 
cortex, which from its structure is evidently an adventitious root. In the 
2nd section a similar root (Pl. 1. Phot. 6, 7.2.) is shown still connected with 
the wood. Immediately to the outside is a free root cut transversely (7.). 
Tt is tetrarch, with a considerable amount of secondary wood, and most of the 
cortex is preserved. This root reappears in the next two sections, but its con- 
nection with the stem is not shown. It agrees, however, as nearly as one can 
expect, with the root-base attached to the stem, and there is little doubt that 
the free root also belongs to the latter. The drawing (Pl. 4. fig. 11) is taken 
from the 4th section (N. 12). Here also the root seems to be tetrarch, the 
four protoxylem-groups corresponding to four principal rays. The secondary 
wood is well developed. Where it is cut somewhat obliquely the tracheides 
show the multiseriate pits on their radial walls as in the stem. The cortex 
contains a certain number of cells with dark or brown contents. So far as 
can be observed, the structure of the root is of the * Aaloaylon” type. The 
characteristic double peripheral layer is not shown, but may have been lost. 
The connection with the stem of H. tilivoides, though not strictly proved, is, 
as we have seen, beyond measurable doubt. 
A very clear root-base in connection with another specimen was figured 
by Williamson (1887, pl. 23. fig. 12). The appendage shown in his fig. 13 
was no doubt of the same nature. 
Specific characters. 
Nothing is more difficult than to fix the value of anatomical characters in 
discriminating species, especially in the case of petrified specimens, where 
practically no other characters are available, 
Fleterangium tiliwoides is most probably distinct from the other forms 
described in this paper, but an anatomical diagnosis is not easy to draw up. 
A few characteristic points may be recalled, 
The primary wood has the tracheides grouped in packets, not unlike those 
of H. shorense, but on the whole less regular (Phots. 2, 3, 6, & 7). 
The pits on the tracheides both of the metaxylem and secondary wood 
commonly have a marked spiral arrangement, often with definite spiral bands - 
between the rows of pits (Williamson & Scott, 1895, p. 764). 
The great development of the phloem and the presence of large dilated 
phloem-rays are perhaps the chief characters, but are of course only recog- 
nizable in the more advanced specimens *. The phloem may equal or exceed 
the secondary wood in thickness. Thus, in specimen 4 (a young stem) the 
secondary wood is about 160 w thick and the phloem about 200 p at the 
same place; at another point they are just equal (245 u). In an older 
stem (specimen 2) the secondary wood ranges from about 570 u to 900 p 
in thickness, the phloem from about 650 p to 740 p. 
* For example, they do not help us in determining whether ZZ. shorense (a young specimen) 
is really distinct. 
