OF COAL-MEASURE PLANT-IMFRESSIONS. 205 
leaf base faint or often absent in napiform types, slight or fairly prominent 
in fusiform examples; rarely if ever occurring above the leaf scar. 
5. CONCLUSIONS. 
From what has been said, I think it is clear that the three species of 
Lepidodendron with which I am concerned here are quite distinct. Great 
variations in the form, size, and shape of the leaf base may occur in all of 
them, but the characters of the leaf scars are more constant and constitute 
the chief but not the only important diagnostic data. The chief peculiarities 
of these three species may be contrasted as follows :— 
Character. | L. lycopodioides. L. ophiurus. | L. loricatum. 
| | — EN 
| | 
Leaf scar ..........,, .. angular slit, rhomboidal. | rhomboidal. 
Orientation of leaf scar .. straight. straight. | usually oblique. 
Prints of leaf sear ...... invisible. faint or rarely vis-| always visible. 
| ible, or only a 
, central print is 
| seen. 
| 
Leaf base .............: fusiform. | fusiform. napiform (subimbri- 
| J . 
| eated ) orfusiform. 
Ornamentation of keel ..| present | absent or very absent. 
feeble. 
| 
Lower angle of leaf base. . ———— | very obtuse. acute. 
The three species agree in the relatively small size of their leaf bases as 
compared with many others (e. g., Z. aculeatum, Sternb.), and in the absence 
of sub-parichnoid prints. There is, however, much variation to be found 
among them, especially in the degree of angularity of the upper extremity 
of the leaf base, whether both its terminations are straight or bent, the 
position of the leaf scar relative to the centre of the leaf base, and the promi- 
nence of the keel. 
Further, in addition to defining these species more accurately, an attempt 
is here made to institute a pure synonymy of these plants, especially with a 
view to establishing the nature of ancient types in the light of modern 
specimens. 
It is shown that L. lanceolatum, Lesq., is identical with L. lycopodioides, 
Sternberg, and that L. simile, Jongmans, is a confusion between that species 
and L. ophturus. 
