On the Leaf Scars of Lepidodendron. S3 



ter. Prof. Lesquereux has said that his L. oculatum, which 

 has much larger leaf scars, is perhaps L. distans in the de- 

 corticated state ; and Prof. Schimper makes oculatum identical 

 with distans, remarking that it differs only in size ; thus im- 

 plying that the size is not distinctive. 



From this extreme width of margin, there is every lesser width 

 down to its entire absence (PI. VII). In some instances a 

 broad margin is greatly narrowed in places. Sometimes the 

 margins are quite suppressed upon two opposite sides of the 

 leaf scars, regarding them as quadrilateral, while a fair breadth 

 of the double margin appears on the other sides. In other in- 

 stances the margin is very much narrowed, or entirely absent, 

 for some distance along each side of the leaf scars, showing 

 greater breadth at the ends of the scars (Fig. 4, PL V). The 

 margin is certainly of little value as a specific character j 

 though its presence may serve to distinguish a section. 



In this species the acuminate ends of the leaf scars are 

 sometimes blended with the margins, caused probably by a 

 strong wrinkle of the medial line extending entirely across 

 the point (Fig. 1, PI. VII). The ends are thus abruptly or 

 rounded obtuse. Sometimes a few leaf scars thus appear upon 

 acuminate specimens. In other instances, the majority or all 

 of the scars are so shortened. Usually only one end of the 

 leaf scar is thus affected, but rarely both ends. When the 

 superior end is shortened, the leaf scar is given more obovate 

 proportions. L. obtusum, Lesq., is a very broad typical 

 aculeatum, with the inferior part of the leaf scar narrowed and 

 the end obtuse ; thus bringing the vascular scar nearly to the 

 middle of the leaf scar. The relative breadth of the leaf scars 

 is not remarkable, even for the typical aculeatum ; though it 

 shows a crowding of the leaves lengthwise of the stem greater 

 than usual. The wrinkle between the vascular scar and the 

 crown is not peculiar to obtusum. The same may be found in 

 Fig. 1, PI. V. Prof. Schimper remarks of L. obtusum, Lesq. : 

 " A Carbondale avec le L. giganteum, dont il pourrait bien 

 repr^senter un rameau principal on un individu moins adulte." 

 And of L. giganteum he says: " Tres-voisin du pr^ce'dent" 

 (L. modulatum), ." les cicatrices sont plus large." It appears 



