Bernard Smith — A Lepidodendroid Stem. 



209 



are not rare, in cases where the stems have to some extent escaped 

 crushing. In profile each one may be conipared with a wall-bracket, 

 in which the shelf is represented by the knob-like projection situated 

 above the leaf-scar. The upper and lower divisions of the field are 

 ornamented by a central keel. 



The leaf-scar is placed, not at the apex of the cushion, as in 

 many species of Lepidodendra, but in a subordinate position, below 

 the apex. The details of the scar are somewhat indistinct. The 

 upper extremity appears to be slightly notched, the lateral angles are 

 obscure owing to the above-mentioned overlap of the bark, and the 

 base is truncated. A print, presumably the leaf-trace scar, can be 

 distinguished, but the preservation is not sufficiently good to enable 

 one to recognise the parichnos. On that portion of the field lying 

 below the leaf-scar a few transverse wrinkles occur. They are 

 usually somewhat oblique, tending to coalesce, and might, as in 

 the case of Lepidodendron Woriheni, be regarded as a specific 

 character. In addition there are a number of other folds, clearly 

 seen in the figure, which run right across the cushion and are 

 continued in the bark on either side. These are almost certainly 

 due to shrinkage, and are not the result of natural growth. 



Lepidodendron sp., from the Middle Coal-measvires near Dudley. Nat. size. 



The most interesting feature presented by this cast is the fact 

 that the leaf-cushions are widely separated. Each cushion is placed 

 at a distance of 1"6 to 1'7 cm. from its neighbour in the same spiral, 

 and 2'3 cm. from its nearest neighbour in the spiral above or below. 

 These measurements are taken from centre to centre of the leaf-scars. 



DECADE V. — VOL. 11. — NO. V. 



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