io WEISS, The Parichnos in the Lepidodendracece. 



the parichnos strand is laid bare as in Potonie's figure, it 

 is by subsequent breaking of a portion of the leaf base. 



In some species of Lepidodendron, however {e.g., L. 

 aculeatum, L. sternbergi, etc.), there appear below the 

 leaf-scar two very definite oblong marks, one on either 

 side of the median line, which, as Scott mentions, seem to 

 have some connection with the parichnos, and to which 

 Potonie compares the scars of Lepidophloios mentioned 

 above. These marks on the leaf-cushion (see Text-fig. 5), 

 which were called "vascular glands" by Stur ('77), 



Fig- 5- — Leaf cushion of Lepidodendron show- 

 ing the lateral pits (l.p.) beneath the leaf-scar, on 

 which the ends of the parichnos strands are seen 

 {par), lig. ^ligular pit. 



have been compared by Solms Laubach ('97) to the 

 orifices on the leaf-stalks of tree ferns, and Potonie ('97) 

 approves of this comparison, though at the same time 

 maintaining that their function is a transpiratory one. 



I have been able to study from a series of sections in 

 the Manchester Museum the nature of these lateral scars 

 and their relation to the parichnos strands in a Lepido- 

 dendron, the internal structure of which showed it to be 

 of the " Harcourtii type," though differing from the 

 typical Harcourtii in some respects.* 



* It resembled very closely the Lepidodendron figured by Williamson in 

 Memoir XIX. , and which Mr. D. M. Watson, who is reinvestigating this 

 form considers to be a different species, and proposes to call Lcpidodm- 

 dron Hickii. 



