194 THE LATE DR. NEWELL ARBER: CRITICAL STUDIES 
quite, terminal. The lateral lines are faint. The keel is faintly ornamented, 
especially on the lower part. 
No. 950. A transition from the quadrate to the fusiform types above 
discussed is seen in the leaf bases figured, enlarged three times, on PI. 10. 
fig. 8. Here the bases measure 6 mm. long and 3°5 mm. broad. The leaf 
scar here has the form of an upright slit. The ornamentation is conspicuous. 
No. 68. An example with small leaf bases from the Middle Coal Measures 
of Barnsley is figured on Pl. 10. fig. 9, enlarged three times. The leaf bases 
here measure 4 mm. long and 2 mm. broad. The carbon has flaked off most 
of the regions around the leaf scar. The keel is very faint and no orna- 
mentation is distinguishable. 
No. 106. Since it appears to have been held that the normal conditions of 
the leaf scar in this species is due to an accidental and unnatural fracture 
of the leaf, it may be well to figure an example of such an occurrence for 
comparison. In fig. 10, Pl. 11, some broken bases of leaves fractured un- 
naturally are seen enlarged. It will be noticed that the appearance in this 
case is quite different from those figured above, in which the leaf base, as left 
attached to the stem by the natural fall of the leaf, is exhibited. 
Further, since this species commonly occurs in various stages of decorti- 
cation, due as we have seen in the case of carbonaceous impressions to the 
tendency of the carbonaceous film to flake off, it may be well to figure here 
some examples in which the decortication is comparatively slight. 
No. 8475. On Pl. 11. fig. 11, some leaf bases from the Middle Coal 
Measure of Bentley, South Statfordshire, are seen slightly enlarged. This is 
an impression in intaglio, and probably slightly decorticated. The leaf sear 
is here a crescentic ridge, inside the angle of which a short vertical ridge 
oceurs. The leaf bases are here exceptional in being separated by double 
bands of bark. 
This species is very common in ironstone nodules and bands in the Middle 
Coal Measures of the Midlands, usually occurring as intaglio impressions, 
more rarely as casts. 
My experience of these fossils leads me to believe that they are almost 
always more or less decorticated, though the leaf bases are rarely crushed. 
No. 754. Fig. 12, Pl. 11, shows (in relief) natural size leaf bases from an 
ironstone cast of this species from the Middle Coal Measures at Bradford, 
Yorkshire. In the position of the leaf scar a small pit occurs, triangular in 
form (isosceles with a narrow base). The keel is very strong, but shows no 
ornamentation. 
No. 755. Fig. 13, Pl. 11, is from a wax cast of another specimen from 
the same locality, this time preserved in intaglio. The irregular area 
around the position of the leaf scar reminds one of the appearance of many 
