i6o 



STUDIES IN FOSSIL BOTANY 



L. esnostense the leaves were acicular, and not very 

 different in form from those of some species of Pinus. 

 Along the under surface, on either side of the midrib, 

 are two furrows, which are very deep near the base 



Fig. 64. — Lepidodendron Hickii Transverse section of leaf v.b., vascular bundle ; 

 some of the large elements round it constitute the transfusion-tissue ; /, furrows 

 in which the stomata are placed. X 60. S. Coll. 51. (G. T. G.) 



of the lamina, but become less marked towards the 

 apex. It is on the epidermis lining these furrows 

 that the stomata are found. They are very numerous, 

 and of the usual bicellular structure. The rest of the 

 leaf is covered by a small -celled epidermis with a 



Fig. 65. — Lepidodendron Hickii. -Epidermis of leaf, with "stomata. X about 300. 

 S. Coll. si. (G. T. G.) 



thick - walled hypoderma below it. The mesophyll 

 consists of a spongy tissue, like that of many recent 

 leaves. This was no doubt the green, assimilating part 

 of the leaf when alive. The middle of the leaf is 

 traversed by a central strand of tissue, enclosing the 

 vascular bundle. The bundle itself is small, but it is 

 surrounded by a wide zone of spiral or reticulated 



