LEPIDODENDRON 155 



the presence of a parenchymatous secondary zone, show 

 a close agreement with Lepidophloios fuliginosus} 

 Curiously enough, the other specimen in question, 

 referred by Mr. Seward to Lepidodendron aculeatum, 

 Sternb., likewise " exhibits an exceedingly close agree- 

 ment with that type of structure which it has been 

 customary to describe as Lepidophloios fuliginosus" 2 It 

 is thus evident that no anatomical distinction can be 

 drawn between the two so-called genera Lepidodendron 

 and Lepidophloios. 



3. Leaves. — We next come to the structure of the 

 leaves of the Lepidodendreae. It is, of course, necessary 

 to distinguish between the leaf-bases or cushions, which 

 remained in connection with the stem, and the leaves 

 themselves, which were thrown off. The great majority 

 of the specimens with structure preserved bear the leaf- 

 bases only ; in the literature it has sometimes happened 

 that the latter have been confused with the actual leaves. 



The external form of the leaf-base has already been 

 described. We have also seen that on the scar, left by 

 the fall of the leaf itself, there are three prints (cf. Fig. 

 55, p. 1 30). The middle one is caused by the vascular 

 bundle, which remained simple throughout the leaf. The 

 two lateral prints, called the parichnos, are, as stated 

 above, of quite a different nature ; a strand of large- 

 celled parenchyma accompanies the leaf-trace through 

 the outer cortex on its lower side, and divides, in the base 

 of the leaf, into two strands, which take up their position 

 to the right and left of the vascular bundle. When the 



1 Scott, "Structure of Lepidodendron obova/mn,'' Ann. of Bot. vol. xx. 

 1906, p. 317 



2 Seward, "Anatomy of Lepidodendron aculea/wn," ibid. p. 378. 



