PREVIOUS INVESTIGATIONS 



when gross lithologic distinctions are not 

 apparent. The results and possibilities pre- 

 sented supplement the results of more ex- 

 tensive investigations by other methods. 



Schopf (1949, p. 511) pointed out that 

 descriptive and taxonomic studies were 

 likely to dominate pollen and spore re- 

 search for many years, simply because the 

 field to be explored is so enormous. In ad- 

 dition he stated, "It does not follow that 

 significant economic results will invariably 

 follow initial exploratory studies; however, 

 the history of paleontology in general is a 

 sufficient insurance that reasonable benefits 

 will come from progress in this work." 



A large part of this report is devoted to 

 the description, some of it very detailed, ol 

 plant megaspores, plus some illustration 

 and discussion of spores that are larger than 

 conventional small spores and may be ei- 

 ther megaspores or small spores, and of pre- 

 pollen, cuticle, and seed membranes that 

 occur in the macerations with the mega- 

 spores. The primary emphasis is on spores 

 from the coals in the upper Mississippian 

 Chester Series and in the Pennsylvanian 

 Caseyville and Tradewater Groups, but 

 those from some of the coals of the Carbon- 

 dale and McLeansboro Groups are de- 

 scribed in order to present a general over- 

 all picture of plant megaspore distribution. 

 Some material of late Mississippian and 

 early Pennsylvanian age from areas outside 

 Illinois also is included for comparative 

 purposes. 



Many of the residues and slides examined 

 had already been prepared in the labora- 

 tories of the Illinois Geological Survey for 

 other studies, and therefore no statistical 

 approach to the relative abundance of meg- 

 aspores from one coal to another, or even 

 in segments in the same coal, could be 

 valid. The terms "rare," "present," "com- 

 mon," and "abundant" used relative to 

 megaspore abundance are necessarily sub- 

 jective because some of the samples were 

 not collected for statistical analysis as were 

 those on which Dijkstra (1946, 1955c) has 

 reported. 



This report,, therefore, is a general and 

 preliminary survey of the occurrence of 



megaspores in upper Mississippian and 

 Pennsylvanian coals, preliminary in that 

 the sampling of the individual coal beds 

 was limited and the examination of spores 

 from coals of the McLeansboro Group < ur- 

 sory. 



Acknowledgments 



I am grateful to J. A. Simon, Head of the 

 Coal Section of the Illinois State Geological 

 Survey, for his interest in and encourage- 

 ment of this investigation, and to Dr. John 

 C. Frye, Chief of the Survey, for his sup- 

 port. Dr. D. H. Swann collected some ol 

 the Mississippian samples and provided 

 guidance in the interpretation of the strati- 

 graphic position of some of the previously 

 collected samples. The advice and guid- 

 ance regarding the stratigraphy of Illinois 

 coals given by Dr. R. M. Kosanke and his 

 contributions to discussions on problems of 

 taxonomy, nomenclature, and interpreta- 

 tion of some of the results made this report 

 possible. 



PREVIOUS INVESTIGATIONS 



Kosanke, whose investigations on the 

 small spores of Pennsylvanian coals of Illi- 

 nois (Kosanke, 1947, 1950, 1954) are well 

 known, has given (1950, p. 7-8) a general 

 history of spore studies from the first ob- 

 servations of fossil plant spores by Witham 

 in 1833 through the important contribu- 

 tions, principally concerning small spores, 

 of the mid-1940's. Many major findings on 

 Carboniferous megaspores also were re- 

 ported during the period beginning with 

 the study by Bennie and Kidston in 1886. 

 Among the important studies done outside 

 the United States are those of Zerndt 

 (1930a, b, c, d; 1931; 1932a, b; 1934; 1937a. 

 b; 1938a, b; 1940), Stach and Zerndt (1931), 

 Kowalewska-Maslankiewiczowa (1932), Sa- 

 habi (1936), Ibrahim (1933), Loose (1934), 

 Wicher (1934a, b), Nowak and Zerndt 

 (1936); from the United States are the stud- 

 ies of Bartlett (1929), Schopf (1936a, b; 

 1938), and Schopf, Wilson, and Bentall 

 (1944). Bailey (1936) briefly illustrated and 

 described some megaspores. 



