xv] 



LEPIDODENDRON 



97 



which constituted the conducting tissue connecting the leaf 

 with the main vascular system of the stem. The two lateral 

 scars (figs. 145, A, p; 146, C,s; 147, p) represent the exposed ends 

 of two strands of tissue, the forked branches of a strand which 

 pass from the middle cortex of the stem into the leaf; this is 

 known as the parichnos, a name proposed by Professor Bertrand 

 in 1891 ^ 



The specimen shown in fig. 141 shows the linear leaves 

 attached to their respective cushions. 



Fio. 141. Lepidodendron Sternbergii. From a specimen in the British 

 Museum (No. v. 12.3.5) from the Coal-Measures of Shropshire. 

 (Nat. size.) 



The lamina has a well-defined median keel on the lower 

 surface and on either side a groove in which sections of petrified 

 leaves have demonstrated the occurrence of stomata (cf fig. 142). 



ii. Leaves and Leaf -cushions. 

 All Lepidodendron leaves, so far as we know, possessed a 

 single median vein only. In some species, as for example m 

 Lepidodendron longifolium Brongn., they have the form of long 



1 Bertrand, C. E. (91) p. 84 : derived from Trapi, by the side of, and ix^os, trace 

 or foot-print. 



