42 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 480 



acknowledged the aid of Morris in plant descriptions, was the first to illustrate 

 isolated fossil megaspores, and Binnie and Kidston (1886) described the Carbon- 

 iferous spores of Scotland. Thiessen and Staud (1923) and Thiessen and Wilson 

 (1924), who used thin sections of coal from the Appalachian region, are credited 

 with being the first to use spores in the identification and correlation of coal 

 seams. Raistrick (Raistrick and Simpson, 1933; Raistrick, 1934) macerated coals 

 and used the isolated spores to correlate coal seams in England. 



Some of the earliest studies in fossil plant spores and pollen in the United 

 States were carried out in the Illinois Basin. Thiessen (White and Thiessen, 1913; 

 Thiessen, 1920), in order to demonstrate some of the botanical constituents in 

 coal, was probably the first to illustrate spores macerated from Illinois coal. 

 Most of his publications, however, concerned his system of petrographic classi- 

 fication of coal . 



Illinois State Geological Survey 



Louis C. McCabe of the Illinois Geological Survey is generally credited 

 with being the first to publish (1932) a paper entirely devoted to a study of macer- 

 ated coal samples from the Illinois Basin. He described and illustrated some char- 

 acteristic spores, cuticles, and woody structures macerated from the 13 coal mem- 

 bers he studied . McCabe recognized the geological and stratigraphic significance 

 of differences in spore assemblages from one coal to another. The botanical and 

 lithological constituents of the Herrin (No. 6 Coal) were the subjects of McCabe' s 

 dissertation (1933). 



O.J. Henbest, who was a field assistant to David White during White's later 

 work in the Illinois Basin, wrote a note (1933a) that was a general discussion 

 of spores and other botanical constituents in macerated residues and thin sections 

 in the No. 6 Coal. His unpublished master's thesis on the floras of certain carbo- 

 naceous shales of Illinois dealt largely with lycopods and lycopod cones from the 

 Francis Creek Shale (Henbest, 1933b). In another paper (1936) he compared size 

 and ornamentation of some modern and fossil lycopod spores. 



Cady (1933) discussed and illustrated macerated megaspores, small spores, 

 resin, and cell structures in Illinois coal and showed how they appear in thin 

 sections . 



Schopf not only made many contributions to our knowledge of Pennsylva- 

 nian plant megafossils of Illinois, but he was also an early and active worker in 

 the study of plant spores. Schopf (1936b, 1938d) investigated in detail the spores 

 of the No. 6 Coal, which is generally the thickest and economically most impor- 

 tant coal in Illinois. He discussed (1938d) maceration techniques, botanical con- 

 siderations (including some of the most lucid biological descriptions of spores to 

 be found), and taxonomy of fossil spores. Most of the study was devoted to a 

 systematic description of the megaspores and prepollen found in coal. 



The Annotated Synopsis of Paleozoic Fossil Spores and the Definition of 

 Generic Groups, by Schopf, Wilson, and Bentall (1944) became a classic in Amer- 

 ican palynology because it provided a basis for a system of classification of fos- 

 sil spores. The publication increased interest in spore studies among paleobotan- 

 ists, and the system of classification it presented was used for many years, es- 

 pecially in the United States. Many of the generic definitions were incorporated 

 by the classification devised by Potonie and Kremp (1954, 1955, 1956) and their 

 followers, which is now widely used. The genesis of the 1944 paper was explained 

 by Schopf: 



