1 6 WEISS, The Parichnos in the Lepidodendracea. 



It will be seen that the radial section of the leaf 

 cushion has somewhat the aspect of that figured by 

 Williamson ('93) (see pi. III., fig. 19), of which he says 

 that the margin of the leaf was " more deeply lobed than 

 usual." This lobing is really the beginning of the lateral 

 pit, his section, though passing through the vascular 

 bundle, being slightly oblique, and not following the crest 

 of the leaf-base. A section a little more out of the 

 median would show even a deeper lobing, as in the 

 reconstructed one, Text-fig. 7. 



In his excellent memoir of Lepidodeitdron selaginoides, 

 Hovelacque. has figured a series of tangential sections, 

 which show that in this species there also existed a pit- 

 like depression running into the body of the leaf cushion. 



Fig. 8. — Radial {a) and tangential (5) sections through the 

 leaf cushion of Lepidodendron selaginoides (diagrammatic after Hove- 

 lacque) showing the inferior groove i.g. (sillon inferieur) which 

 corresponds to the lateral pits of other Lepidodendra. 



lig.p. = ligular pit. v.b. = vascular bundle. par. = parichnos. 



This is plainly seen in the figures {figs. 2 and 3 of pi. IV.) 

 •of his memoir, and still more clearly in fig. 3 of pi. v. 

 To this depression, which is shown in radial view on fig. 6, 

 pi. VII., Hovelacque has given the name of "sillon inferieur," 

 as it comes close below the leaf scar. It differs, as is 



