16 



ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 492 



in cross section but show a short 

 part of it as an inclined ribbon. 

 We know that the vascular bundle 

 originally grew upward and outward. 

 If we combine this information with 

 the knowledge of the position of 

 the outside of the stem in the 

 specimen, we can determine the nat- 

 ural position of the stem fragment. 

 It becomes clear from this specimen 

 (ISGS PB-1298) that the indentation 

 of the outer vascular bundle is in 

 the lower (abaxial) side and that 

 the inner trace is in the upper 

 part of the scar. 



10 cm 



Text fig. 13 - Reconstruction of part 

 of the stem of Artisophyton mclayi 

 after specimen ISGS PB-1298. This 

 reconstruction demonstrates the 

 natural orientation of leaf scars 

 in Artisophyton. 



REFERENCES 



Andrews, H. N., and Jeanne Doubinger, 1970, Genre Caulopteris Lindley et 

 Hut ton, 1832, p. 192-200, and Genre Megaphyton Artis, 1825, p. 

 200-201, in Boureau, E. (ed.), 1970, Traite de Paleobotanique, 

 v. IV, part 1, Filicophyta. Paris: Masson et Cie., 519 p., 

 378 figs. 



Artis, E. T., 1825, Antediluvian phytology, illustrated by a collection 

 of the fossil remains of plants, peculiar to the coal formations 

 of Great Britain. London: 13 p., 24 pis. with 24 p. of 

 explanation. 



Corda, A. J. , 



1845, Flora Protogaea - Beitrage zur Flora der Vorwelt. 

 Berlin: Calvary und Co., 128 p., 60 pis. 



Cor sin, Paul, 1948, Reconstitutions de Pecopteridees: genres Caulopteris 

 Lindley and Hutton, Megaphyton Artis et Hagiophyton nov. gen.: 

 Annales du Societe Geologique du Nord, v. 67 (1947), p. 6-25, 

 4 figs. , 4 pis. 



