XIV L YCOPODINE^ 507 



most characteristic ones of the Coal-measures, where their 

 remains occur in enormous cjuantities. While evidently related 

 to the modern Lycopodineai, they were different in some 

 respects, especially the gigantic size of some species, which 

 reached tree-like proportions. The leaves were deciduous, 

 and in falling off left the characteristic rhombic leaf-cushions 

 exposed. The structure of the stem ^ is not unlike that of 

 Lycopodiuui^ and shows a central bundle-strand surrounded by 

 a massive cortex, through which pass the leaf-traces. In some 

 cases the increase in thickness of the stem was due mainly to 

 the cortex, but specimens have been found in which there was 

 an undoubted secondary thickening of the vascular bundles, 

 quite similar to those in Gymnosperms. 



The sporangia have been preserved with wonderful perfec- 

 tion in a few cases, and their structure is well known." In 

 position they correspond to those of Lycopodium, but were 

 heterosporous, somewhat like Selaginella, but usually the 

 macrospores were much more numerous. These sporangial 

 strobili of Lepidodendroii were first described under the name 

 Lepidostrobus. Bovver,^ who has recently carefully examined 

 their structure, states that the cavity of the large sporangium is 

 divided by incomplete trabeculae, somewhat as in Isoetes. 



Probably related to the Lepidodendreae are other large 

 lycopodinous forms occurring in the same geological formations, 

 and grouped together under the name Sigillarieae. They show- 

 similar markings upon the surface of the stems, but their struc- 

 ture and fructification are much less perfectly known than is 

 the case with the Lepidodendreae, with which, however, they 

 seem to agree in the main. 



The genus Stiginaria has been conclusively shown to 

 be nothing but the roots or rhizomes of Lepidodendreae or 

 Sigillarieae. 



The LepidodendrejE have been traced as far back as the 

 Lower Devonian,'* but the Sigillarieae are not know^i certainly 

 below the Coal-measures, and both groups disappear before the 

 end of the Carboniferous period. 



^ Solms-Laubach (i), p. 215. ^ Bower (15). 



3 Bower, I.e. p. 527. * Solms-Laubach (2), p. 194. 



