530 Note . 
The young roots much resemble the smaller adventitious roots of 
Marattiaceae. 
3. Secondary Tissues of the Root . — These are beautifully preserved, 
and are found at all stages of development. The cambium is often 
specially clear. Secondary growth began opposite the phloem-groups, 
and the secondary wood is generally interrupted by large rays 
opposite the protoxylem-strands. The secondary tissues resemble 
those of the stem. The whole process of secondary growth was 
perfectly normal, as in dicotyledons at the present day. 
4. Branching of the Root . — The numerous specimens showing 
branching prove that the rootlets were endogenous, and that they 
arose opposite the protoxylem-groups of the main root. 
D. Habit and Dimensions of the Plant. 
In none of our authentic specimens is the stem more than 4 cm. in 
thickness. Certain cortical impressions, belonging to much larger 
stems, have been referred to Lyginodendron } but on inconclusive 
grounds. 
There is one large specimen showing structure, in which only the 
secondary wood and portions of the pith are preserved. So much of 
the structure as remains agrees closely with that of Lyginodendron. 
This specimen may have reached a diameter of 30 cm. or 40 cm., and 
establishes a certain probability that L. Oldhamium , or some allied 
species, may have attained the dimensions of a small tree. 
The ordinary specimens must have had upright stems of consider- 
able height, bearing spirally-arranged, compound, fern-like leaves, 
separated by internodes about an inch long. The lower parts of the 
stem gave off on all sides numerous adventitious roots. 
The entire absence of fructification is remarkable, considering the 
great frequency and admirable preservation of our fossil. It may be 
explained, either on the hypothesis that the leaves bore very caducous, 
fern-like sporangia, or by supposing that our material consists entirely 
of immature specimens. 
