40 



REFERENCES 



Read, C. B., and Campbell, Guy, Prelimi- 

 nary account of the New Albany shale 

 flora: Amer. Midland Nat., vol. 21, pp. 

 435-453, 1939. 



Reed, F. D., Structure of some Carboniferous 

 seeds from American coal fields: Bot. 

 Gaz., vol. 100, (4), pp. 769-787, June 1939. 



ScHiMrER, W. Ph., Traite de Paleontologie 

 Vegetale, vol. 2, Paris, 1870-1872. 



ScHOPF, J. M., A significant collection of 

 American coal-balls: Chronica Botanica, 

 vol. 4, pp. 384-385, Sept. 1938, a. 



SciioPF, J. M., Spores from the Herrin (No. 

 6) coal bed in Illinois: Illinois Geol. 

 Survey Rept. Inv. No. 50, pp. 1-73, 

 1938, b. 



ScHOPF, J. M., Two new Lycopod seeds from 

 the Illinois Pennsylvanian: Trans. Illi- 

 nois Acad. Sci., vol. 30, pp. 139-146, 

 1938, c; Illinois Geol. Survey Cir. 28, 

 1938 c. 



ScHOPF, J. M., Lepidocarpon: in Janssen, 

 Ray, Some fossil plant types from Illi- 

 nois: Illinois State Museum Scientific 

 papers, vol. 1, pp. 39-45, Springfield, Illi- 

 nois, 1940. 



ScHOPF, J. M., Notes on the Lepidocarpaceae: 

 Amer. Midland Nat., vol. 25, pp. 548-563, 

 1941; Illinois Geol. Survey Cir. 73, 1941. 



Scott, D. H., On the structure and aflEinities 

 of fossil plants from the Paleozoic rocks. 

 — IV. Lepidocarpon: Phil. Trans. Roy. 

 Soc. Lond., B., vol. 194, pp. 291-234, 1901. 



Stopes, M. C, and Watson, D. M. S., Origin 

 of calcareous concretions in coal seams 

 known as coal-balls: Phil. Trans. Roy. 

 Soc. London, B., vol. 200, pp. 167-218, 

 1909. 



Stur, D., Ueber die in Flotzen reiner Stein- 

 kohle Enthaltenen Stein-Rundmassen 

 und Torf-Spharosiderite: Jahrbuch der 

 Kaiserlich-Koniglichen Geol. Reichsan- 

 stalt, Wien, vol. 35, pp. 613-648, 1885. 



Walton, John, Scottish Lower Carbonifer- 

 ous plants: The fossil hollow trees of 

 Arran and their branches: Trans. Roy. 



Soc. Edinburgh, vol. 58, (2), pp. 313-338, 

 1935. 

 Wanless, H. R., Pennsylvanian correlations 

 in the Eastern Interior and Appalachian 

 coal fields: Geol. Soc. Am. Spec. Papers, 

 No. 17, pp. 1-130, 1939. 



Watson, D. M. S., On Mesostrohus, a new 

 genus of Lycopodiaceous cones from the 

 Lower Coal Measures, with a note on 

 the systematic position of Spencerites : 

 Ann. Bot., vol. 23, pp. 379-397, 1909. 



Watson, D. M. S., On the structure and 

 origin of the Ulodendron scar. Ann. Bot. 

 28, 481-498, 1914. 



Wellee, J. Marvin, Geology and oil possi- 

 bilities of extreme southern Illinois: 

 Illinois Geol. Survey, Rept. Inv. No. 71, 

 pp. 1-71, 1941. 



White, David, Environmental conditions of 

 deposition of coal: Trans. Amer. Insti- 

 tute of Mining and Met. Engineers, vol. 

 71, pp. 3-23, 1925. 



Zalbssky, M. D., On the discovery of the 

 Calcareous concretions known as coal- 

 balls in one of the coal seams of the 

 Carboniferous strata of the Donetz 

 Basin: Bull. Acad. Imp. des Sci., pp. 

 477-480, 1910. 



Zeiller, R., Etude sur le Lepidostrohus 

 hromnii (linger) Schimper: Mem. de 

 I'Acad. des Sci., Paris, vol. 52, pp. 1-67, 

 1911. 



Zeiller, R., Cones de Fructification de 8igil- 

 laires: Ann. Sci. Nat., Bot., 6th ser., vol. 

 19, pp. 256-280, 1884. 



Zerndt, Jan, Les Megaspores du Bassin 

 Houiller Polonais: premiere partie, 1934. 

 Ibid., deuxieme partie, 1937: Acad. 

 Polon. des Sci. et des Lettres, Comite 

 des publications Silesiennes. Travaux 

 geologique, Nos. 1 and 3. 



Zerndt, Jan, Megasporen des Saarkarbons: 

 Paleontographica, vol. 84, Abt. B, pp. 

 133-150, 1940. 



Zimmermann, W., Die Phylogenie der 

 Pfianzen: Gustav Fischer, Jena, 1930. 



