100 FLORA OF LOWER COAL MEASURES OF MISSOURI. 



arrangement, the rachis and racliial lamina together with the bases of the 

 pinnules having been lifted away. It seems probable that these pinnules 

 are somewhat convex, curving out away from the lamina, and that normally 

 they are somewhat raised, oblique to the plane of the rachis. The nerves 

 are broad and flat, forking dichotomously and passing somewhat flabellately 

 into the not very long, rather blunt teeth. 



It is a noteworthy fact that the surface of the primary (!) pinnae in 

 most of the specimens is concave or convex, the ends, the lateral pinnae, 

 being reflexed or rolled back from the side bearing the pinnules. Thus in 

 one fragment the lateral pinnaB are rolled halfway back. Fig. 1 , PI. XLVII, 

 representing the axial side, while Fig. 2 shows the opposite, sides of the 

 body nearly covered by the reflexed pinnae. The pinnules formerly cover- 

 ing what is now the outer surface are entirely lost. 



Among the Paleozoic plants thus far made known the form which 

 seems most nearly related to this sj^ecies is the ScMzopteris pinnata of Grand 

 'Eury^ or the Androstacliys frondosus of the same author," both of which 

 have been referred by Zeiller^ to Zygopteris, since Renault^ had already 

 discovered in the fronds of Scliizopteris pinnata the structure characteristic 

 of Corda's genus.^ Araucarites spicceformis Germar'^ has several points (if 

 strong resemblance, especially the characters of the axis and the arrange- 

 ment of the lateral pinnge, and it perhaps belongs, as Grand 'Eury and 

 Zeiller have suggested, in the same group. The rachises of both orders 

 in our plant are much more lax aj)parently than in the examples figured by 

 Grand 'Eury or Zeiller,^ while the rachial lamina, which is so prominent a 

 feature in the Missouri fossil, seems hardly represented in Zygopteris pin- 

 nata, the pinnules of which are lateral, though perhaps not in the same 

 plane, with lax fibrovascular bundles passing out thi'ough the limb from 

 the whole width of the pinnule. In our plant, on the contrary, the broad 

 lateral lamina is not striated by the passage of any bundles, the vascular 

 branches being confined to the bands which pass from the rachis of the 

 lateral pumge to the cicatrices seen in the rachial lamina. 



'Fl. carb. Loire, 1877, p. 200, pi. xvii, fig. 1. 



2 0p. cit., tig. 3. 



' Fl. foss. liouill. Commentry, vol. i, p. 77. 



^Ann. Sci. Nat., (6) bot., vol. iii, p. 23, pi. i, figs. 12, 13. 



^ Flora d. Vorwelt, 1845, p. 81. 



" Verst. Steink. LobejUn'u. Wettin, p. 94, pi. xxsiii, figs. 1,2. 



■ Fl. foss. liouill. Commentry, vol. i, Atlas, pi. xxxii, figs. 5-7. 



