EXTERNAL MORPHOLOGY OF THE STEMS OE CALAMITEs. oll 
external surfaces of the internodes appear to be strongly striated longitu- 
dinally, especially in the case of C. majus (Pl. 28. figs. 5, 7, and 9) and 
C. verticillatus (Pl. 94. fig. 18). 
This ribbing is even more marked in the foreign species C. Parrani 
(Grand Eury)*. 
In the case of C. conyenius (Pl. 28. fig. 2) we appear to have a quite 
unique type so far as Britain is concerned, in which the internode has two 
distinct regions : a central, with a smooth external surface, and a sab-nodal, 
above and below the central area, in which the internode is strongly striated 
longitudinally. The same feature is also seen in the foreign specimen 
Calamodendron striatum of Renault f, and in some examples of C. multiranus, 
Weiss f. 
In the case of C. (eruciatus) Fürsteri of Sterzel f. the internodes between 
the nodal regions are not smooth, but are finely striated. The internodes 
are also, here, much longer than in C. congenius. 
Beginning with those cases in which the external surfaces of the inter- 
nodes are smooth, in the sense that they are not longitudinally striated, we 
have but few examples in which the surface is not relieved by ornamentation 
in some form or other. In the ease of C. Suckowi (Pl. 24. figs, 11-12) the 
surface is smooth and featureless, but faint sub-cortical striations can be 
recognised. In the undetermined specimen shown on Pl. 24. fig. 19, which 
may possibly represent the external surface of Calamites Cisti, the surface is 
smooth with a delicate sub-cortical ribbing. In other species the bark is 
ornamented, as it were, in various ways. Sometimes large and well-marked 
cracks, or shallow grooves, essentially short and irregular, and disposed in 
various directions, are present. The finer examples of these grooves may 
be distinguished as wrinkles. 
For instance, in C. britannicus (Pl. 98. fig. 1) there are two series of these 
furrows or wrinkles, the greater part of the internodes being wrinkled 
transversely, whereas below the node there is a series of short vertical 
grooves, In C. rugosus (Pl. 28. figs. 3 and 6) the ornamentation is delicate, 
and though characteristic is somewhat difficult to describe, the surface of 
the internode being faintly rugose with numerous crowded irregular shallow 
pittings. In the case of C. paleaceus, tur §, the surface of the internode 
appears to us to be almost identical. 
In C. Goepperti (Pl. 24. fig. 13) one of the features by which this species 
can be readily recognised is the presence of a number of vertical continuous 
or discontinuous deep cracks or furrows in the bark, the grooves being 
* Grand! Eury (1890) p. 211, pl. 14. figs. 6-8. 
+ Renault (1890) [in Renault & Zeiller (1888)] p. 457, pl. 54. fig. 5. 
t Kidston & Jongmans (1915) pl. 114. fig. 1, pl. 117. fig. 1, pl. 127. 
$ Sterzel (1893) p. 59, pl. 7. figs. 5 & 6, pl. 8. figs. 1-3. 
| Kidston & Jongmans (1915) pl. 155. fis. 2-3. 
