LEPIDODENDUOX. 155 



being the scar of the leaf-trace bundle, while the two lateral 

 together constitute the parichnos. 



Leaves (Lepidophyttum) simple, acicular, elongate, linear or 

 linear-lanceolate, uninerved. 



Cones (Lepidostrobus) heterosporous, or possibly isosporous in 

 some cases, borne on the terminations of the finer branches, or 

 arranged spirally, or in two opposite rows on special fructiferous 

 branches (Ualonia and Ulodendron in part). Sporangia large, 

 elongate, borne singly on the upper surface of the spirally 

 arranged sporophylls. 



Rhizomes (Stigmaria in part) cylindrical, diverging from the 

 base of the ti'unkas four main branches, which repeatedly bifurcate. 

 Rootlets cylindrical, tapering distally, arranged quincuncially on 

 the rhizome. Rootlet-scars circular, with a circular depression 

 between the outer and somewhat raised rim, and the central vascular 

 print. 



The two more important genera of this family are Lepidodendron 

 and Lepidopfdoios. These types are now known in great detail, 

 both as regards their external morphology and internal anatomy. 



Genus LEPIDODENDRON, Sternberg, 1820. 

 [Flora Vonvelt, Heft i, pp. 20 and 25.] 



Stem arborescent, dichotomously branched above. The persistent 

 leaf -bases are vertically elongate, usually longer than broad, 

 approximate, more rarely distant and separated by bands of bark. 

 The leaf-scar, generally placed slightly above the centre of the 

 leaf-cushion, is rhomboidal, and as a rule somewhat broader than 

 long. The leaf-scar bears three prints, the central leaf-trace scar, 

 and the two lateral scars of the parichnos. 



In some species a small scar, that of the ligule, occurs above the 

 leaf-scar. The leaf-cushion below the leaf-scar in many species 

 possesses a median ridge or keel, with or without transverse notches 

 or grooves. The leaves (Lepidophyttum in part) are simple, 

 acicular or elongately linear, uninerved. The cone (Lepidostrobus 

 in part) consists of an axis bearing crowded sporophylls or bracts, 

 usually spirally arranged, each sporophyll bearing a single, large, 

 radially elongate sporangium on its upper surface. Rhizome 

 (Stigmaria in part), see above. 



