A PALEOZOIC ANGIOSPERM 



345 



pure balls which contain only negligible quantities of pyrite are 

 rare, but one collected by the Illinois State Geological Survey at 

 Harrisburg, Illinois, O'Gara Mine Number 9, coal seam Number 5, 

 satisfied all reasonable demands for purity. It was sectioned by 

 Mr. J. H. Hoskins, of the Department of Botany at the University 

 of Chicago, and described by him.^ 



The coal-ball in question contained an angiospermic stem of 

 distinct monocotyledonous affinity. The stem portion was about 

 4 cm. long and 2 cm. in diameter. Throughout the cross-section 

 (Fig. i) are scattered numerous endarch collateral vascular bundles. 



Fig. I. — Diagram of cross-section of stem with peripheral groups of scleren- 

 chymatous cells and scattered collateral bundles; xylem shown in black; rootlet 

 has penetrated one side of stem (after Hoskins) . 



The phloem is oriented toward the periphery. The detail of a 

 single bundle with phloem preserved is shown in Figure 2 . Surround- 

 ing the xylem is a sheath of sclerenchymatous fibers, not extending 

 completely around the bundle, nor present at the phloem side. 

 Between this sheath and the heavy-walled xylem cells are usually 

 thin-walled parenchyma. Throughout the cross-section are what 

 were probably mucilage ducts. Placed near the periphery of the 



' J. H. Hoskins, "A Paleozoic Angiosperm from an American Coal-ball," Botan- 

 ical Gazette, Vol. LXXV (1923), pp. 390-97. 



