INTERNODES OF CALAMITES, 495 
undulatus, yet as grouped according to this scheme all three agree in having 
Curve Ш the branches at the penultimate node, 
Calamites undulatus: measurements in and in thus conforming with the 
millimetres. typical tree-habit. 
Other specimens of Calamites un- 
dulatus described by Jongmans show 
the branch-scars specially in the neigh- 
bourhood of the shortest internodes. 
Very interesting confirmatory evi- 
dence is supplied by Jongman's speci- 
“i” of C. undulatus, of which he 
gives a diagram (Figure 12 in his 
paper) This shows branch-scars at 
all the nodes, but the sears at the 
men 
base of the shortest node are con- 
Л spicuously larger than those at the 
| | other four nodes. Such would be 
the normal condition on the year's 
shoot of trees in which a short inter- 
node is near the tip. 
III. Nature of the Leaf-scars on 
Calamites. 
I could find no information as to 
| the dimensions or shapes of the leaf- 
scars in the measured Calamites, vet 
it seemed possible that investigation 
of the specimen described by Kidston 
(Calamitina varians, var. inconstans), 
with its numerous nodes, might show 
variations similar to those in the 
year's shoot of modern plants; and 
in particular that the leaf-scars in the 
middle of each cycle might be larger 
than and of a different shape from 
the others. Dr. Е. J. Lewis was 
so good as to examine the speci- 
mens from this point of view, and his 
observations, which are appended, 
clearly prove that such is the case. 
In this connection it may be men- 
x 3€ tioned that Horwood's measurements 
of the leaf-sheaths of living Equiseta show a gradual increase in the length 
as the stem is ascended. 
2m 2 
