3 2 I 
Two Palaeozoic Stems from India . 
information in regard to the primary bundles, either at the medulla or 
during their exit as leaf-traces. It may be inferred, however, from the 
absence of foliar strands in the innermost zone of xylem which has been 
preserved, that they were ephemeral in their nature, rather than persisting 
for several years after the fall of the leaf itself, as is the case in certain 
Mesozoic and living Conifers. In places, traces of the bark may be found, 
but so indifferent is the state of preservation that no details of its structure 
could be ascertained. The woody cylinder itself has suffered less from the 
ravages of time, and a microscopic study reveals all the details of its 
organization. The most striking feature shown in the transverse section 
(Fig. i, PL XVII) is the presence of distinct annual rings. That these are 
true growth rings cannot be questioned ; they surround the entire stem, and 
it is possible to trace the gradual diminution in size and thickness of wall in 
passing from spring to summer tracheides, followed by the abrupt transition 
to the larger lumened, thin- walled elements of the ensuing year. The 
rings are remarkably broad, extending sometimes from io to 12 mm. This 
character is more striking when compared with that of living Conifers. In 
measurements made by the writer on a representative collection of woods, 
the average width of annual ring was found to be from 1 to 3 mm. In many 
pines 4 mm. is not uncommon, and in the Podocarps and Taxads it is 
usually as low as 0*5 mm. Penhallow 1 has given figures agreeing in the 
main with these. The only cases at all comparable with this Indian 
specimen were Cnpressinoxylon chayennense (Cretaceous) and Pityoxylon 
Alder soni (Tertiary), the rings of the former being 10 mm. in width, and of 
the latter 6-9 mm. To return to the wood in question, their number 
indicates that it had reached an age of five years, but, as noted above, the 
tissues adjacent to the pith have disappeared, and it is possible that one or 
two years’ increment may thus have been obliterated. Even so, a much 
more rapid rate of growth is indicated than that shown by the Conifers of 
to-day. 
The wood itself conforms in a general way to the Dadoxylon type so 
common at that time throughout the world. The tracheides are small, and 
the pits seem confined to the radial wall. The size and arrangement of 
these pits are, however, quite distinctive, and serve to differentiate this 
specimen from others of a similar nature. It will be noticed from Fig. 3 
that they practically never stand alone, but are rather in groups of 2-5. 
Two is the prevailing number, and in this case they are almost invariably 
opposite. Groups of three are also frequently seen, either all abreast, or 
one between and above the others. Rarely four may be seen on the same 
horizontal line, but this is unusual, though groups of four are not uncommon. 
In no case is there the slightest indication of a ‘ bar ’ or ‘ rim of Sanio ’ 
between the pairs of opposite pits. This grouped condition is characteristic 
1 Penhallow (1907). 
