ORGANIZATION OF THE FOSSIL PLANTS OF THE COAL-MEASURES. O27 
its foliage. Now we are in a somewhat better position, though our information on 
this subject is still imperfect. 
One of the most important of the additional specimens is that of which a part is 
represented, in longitudinal section, in Plate 84, fig. 47. This section passes through 
a node, which is very clearly shown, and corresponds well with the nodes of other 
species of Sphenophyllum. On both sides the bases of the leaves are evident. Below 
these the cortex is dilated for some distance. The vascular bundles appear to have 
passed out obliquely ; on one side the outgoing trachez could be seen. The identity 
of this specimen with the other Burntisland examples of Sphenophyllum is sufficiently 
proved by the structure of the secondary wood. If fig. 478, which is taken from the 
specimen with the node, be compared with fig. 50, which is taken from one of the 
largest specimens, the agreement in structure is manifest, the peculiar medullary rays 
being especially characteristic. 
We have another preparation which shows something of the leaves. This is an 
approximately transverse section of a very young stem (see Plate 83, fig. 46). A 
part of the whorl of leaves is shown, with two vascular bundles passing out through 
it. Judging from this specimen, the leaves in each verticil could not have been very 
numerous ; probably not more than six. They were evidently coherent for some 
distance from their base. 
Primary Structure, 
The primary structure of the stem of S. insigne is on the whole similar to that of 
S. plurifoliatum. The cortex of the young stem has the same characteristic form as 
seen in transverse section. ‘There is a marked depression opposite each of the 
concave sides of the triarch strand of wood (see Plate 76, photograph 23; Plate 83, 
fig. 45). 
The primary xylem agrees in general anatomical features with that of the former 
species. Here also the triquetrous strand of trachez is quite solid, and destitute of 
parenchymatous elements of any kind. The trachee are of smaller size than those 
of S. plurifoliatum. Towards the middle of the strand they are pitted ; their pits 
are very variable in form; sometimes they are oval, and not unlike those of the 
former species ; often, however, they are more transversely elongated, and approach 
the scalariform type. Towards the angles of the strand the elements become rapidly 
smaller; at each corner there is constantly an intercellular space or canal, which 
affords a good distinctive character from S. plurifoliatum, in which such canals are 
never found (Plate 76, photograph 23; Plate 83, fig. 45). Surrounding the canal are 
spiral trachese, which are much more frequent here than in the last species. 
Fragments of spirals are also often found in the canal itself (see Plate 85, fig. 53). 
It would be rash to assume that the canals existed, as such, during life. It is 
possible that they may represent the position of thin-walled tissue which acemopanied 
the spiral elements. It is, however, equally likely that they were actual lacune, 
MDCCCXCIV,—B, 6 ¢ 
