132 Structure of Lepidodendron and Sigillaria. 



Prof. Schimper unites, are undoubtedly variations of S. lepido- 

 dendrifolia. 8. obliqua was established upon Wilkesbarre 

 specimens. 8. sculpta, Lesq., in Rogers' Geol. of Pennsyl- 

 vania, is probably another distorted form. Prof, Newberry's 

 specimens of 8. l&pidodendrifolia show similar variations ; and 

 so does Brongniart's original figure, 



I believe, also, that future comparison will prove the iden^ 

 tity of 8. stellata, Lesq., with 8. lepldodendrzfolm. All the 

 characters of the leaf-scars of these two forms are precisely 

 identical. Surely this is much more important, as a bond of 

 union, than the difference in direction of the cracks between 

 the scars is a reason for their separation. The striation or 

 wrinkling is a cracking of the bark due to expansion ; and the 

 direction of the furrows is determined by the directions of 

 expansion, which might be influenced by accidents of growth. 

 For this reason, the peculiarity of wrinkling is not a reliable 

 feature. I have observed upon 8. lepidodendrifolia a slight ten- 

 dency toward stellate wrinkling ; yet, the radiation of the furrows 

 of 8, stellata is so very pronounced, that I am not confident of 

 the unity of these forms. But, it may well be suggested that 

 ~8. stellata is perhaps a peculiar expansion of a Brardii form 

 which had the leaf-bases extremely elevated. A fine specimen 

 of 8. stellata in Prof. Newberry's collection shows very dis- 

 tinctly the contiguous hexagonal areas of the enlarged and 

 still elevated leaf -bases. This peculiar form seems not to have 

 occurred except in the anthracite fields of Pennsylvania, and 

 is there extremely rare. 



S. spimdosa, Germ., appears to agree, in the character of 

 its leaf-scars, with 8.. lepidodendrifolia ; and the markings 

 which have been regarded as the points of attachment of succu- 

 lent spines — whence the name — agree in shape with the fruit- 

 scars of 8. lepidodendrifolia / and also with those of 8. 

 Lorwayana Dawson. Prof. Schimper suggests that these marks 

 are the scars of adventitious rootlets. He could not consider 

 them the scars of strobile fruits. If they were the points of 

 attachment of rootlets, we might expect some alteration of the 



