50 



PAL^ONTOLOGICAL BOTANY. 



by peculiar scale-like scars (Fig. 41), hence the name of the 

 plant (XcTTtg, a scale, and hivZpov, a tree). Although the scars 

 on Lepidodendron are usually flattened, yet in some species 

 they occupy the faces of diamond-shaped projections, elevated 

 one-sixth of an inch or more above the surface of the stem, and 

 separated from each other by deep furrows; — the surface 

 bearing the leaf being perforated by a tubular cavity, through 

 which the bundle of vessels that diverged from the vascular 



Fig. 42. Fig. 43. 



axis of the stem to the leaf passed out. The linear or lanceo- 

 late leaves are arranged in the same way as those of Lycopo- 

 diums or of Conifera3, and the branches fork like the former. 

 The internal structure of the stem is the same as that of Sigil- 

 laria. The fruit of Lepidodendron and allied genera is seen 

 in Lepidostrobus and Triplosporites (Figs. 42, 43 ; Plate III, 



Fig. 42. Fructification of Lepidodendron, showing its cone-like form 

 and spiral arrangement of scales. It is called Lepidostrobus Dahadianus 

 by Schimper, but it is probably Triplosporites. 



Fig. 43. Longitudinal section of the fructification, showing central 

 axis and scales carrying sporangia. The upper sporangium contains 

 microspores, the lower macrospores ; hence it has the character of 

 Triplosporites. 



