206 DR. D. H. SCOTT : 
where its course has been followed. Secondary wood is present, often 
reaching a considerable thickness. The secondary and metaxylem tracheides 
have multiseriate bordered pits. 
In three species, C. Saturni, C. annularis, and C. americana, the leaf-bases 
are present and have the structure of Aalymma, containing a number of 
bundles derived from the subdivision of a single leaf-trace. 
In C. americana, and probably in C. annularis, the pith is a * mixed” one, 
containing tracheides, and the structure therefore protostelie (Scott & 
Jeffrey, 1914, p. 318). The differences between the species will be discussed 
in the second part of the paper. 
I. Tug Lear-rrace OF Calamopitys americana. 
Tn the paper, by Prof. Jeffrey and myself, on Fossil Plants from Kentucky, 
we showed that in C. americana the leaf-trace, starting as a single bundle, 
divides into two as it passes through the zone of secondary wood, thus 
entering the cortex as two distinct strands (Scott & Jeffrey, 1914, p. 321). 
Certain difficulties, however, remained. In one case the original bundle was 
found to divide twice, and there was some doubt as to the nature of the first 
division, though it seemed probable that it served to separate the trace as a 
whole from a reparatory strand which remained in the stele, while the second 
division represented the duplication of the trace itself (l.e. p. 323). Neither 
had we, at that time, any section clearly showing the two bundles of the 
trace where they pass out of the secondary wood. 
I have since had a new series of sections cut for me by Mr. Hemingway, 
which shows the whole process of division of the trace quite clearly, as well 
as its relation to the reparatory strand. The new evidence only confirms our 
previous conclusions, but it makes the case clear, where it was obscure before, 
and therefore seems worth bringing forward. 
The fragment from which the new series was cut was about an inch long, 
and 20 transverse sections were obtained from it. It forms a portion of the 
stem marked F, one of the larger specimens, the whole stem measuring about 
40 mm., with a pith about 13 mm. in diameter. The uppermost section of 
the series lies just below a section previously figured (l. e., Pl. 29. Phot. 22 
and PI, 30. Phot. 28), so that the origin of the two bundles there shown can 
be followed. In the original section only one bundle was complete, the other 
fragmentary ; in the new series both are complete, from their first separation 
onwards. A selection of the slides, illustrating the most important changes, 
has been photographed (Pl. 6. Phots. 1-10). The series is followed from 
below upwards. 
In the lowest section (Phot. 1) the trace in question is still at the margin 
of the “pith”; it has only just begun to move out wards, but its nature, as an 
outgoing trace, is indicated by the fan-lihe arrangement of the rows of 
