MAZOCARPON OEDIPTERNUM 



The present paper by no means ex- 

 hausts the possibilities of botanical 

 study on the Calhoun collections of 

 Mazocarpon. It seems desirable, how- 

 ever, to publish the data which are now 

 available so that they may be of use. 

 A complete study of this excellent ma- 

 terial will require much more time. 



ACKNOWLEDGMENTS 



The author wishes to express his ap- 

 preciation to Dr. G. H. Cady for en- 

 couragement during the progress of this 

 work, and particularly for his careful 



reading of the manuscript and his con- 

 structive comments. Mr. Revilo Oliver 

 of the University of Illinois Classics De- 

 partment has aided in the selection of 

 the new scientific names. Professor L. 

 M. Cline of Iowa State College, Ames, 

 has kindly provided correlations for sev- 

 eral coal-ball occurrences in Iowa. The 

 assistance of Professor H. R. Wanless 

 and Dr. J. M. Weller in stratigraphic 

 interpretation and the cooperation of 

 other members of the Survey staff is 

 gratefully acknowledged. Many of the 

 sections used in this study of Mazocarpon 

 have been prepared by Mr. E. Allen 

 Piatt. 



AGE RELATIONS OF COAL-BALL PETRIFACTIONS WITH 

 REFERENCE TO THE GENUS MAZOCARPON 



The occurrence of Mazocarpon in the 

 upper McLeansboro Calhoun coal-ball 

 horizon was first reported by Graham 

 in 1935. A published list (Fisher-Noe, 

 1939) of coal-ball plants from the Cal- 

 houn (Richland County) locality refers 

 to this form as Mazocarpon shorense 

 Benson, although M. shorense had been 

 reported previously only from much 

 older lower Westphalian strata in west- 

 ern Europe, and Graham's mention of 

 M. shorense in this connection was only 

 comparative. It now appears that the 

 Calhoun Mazocarpon, i. e., M. oedipter- 

 num, is distinct from Mazocarpon shor- 

 ense. The improbability of the species 

 being the same is evident from consid- 

 eration of the difference in age between 

 well known European and American 

 coal-ball horizons. 



The horizon at which any fossil speci- 

 men is found is important in considera- 

 tions of its relationship and phylog- 

 eny. Hence it is essential that the ge- 

 ological age relations be critically con- 

 sidered before conclusions are drawn as 

 to the biological relationship of species 

 of Mazocarpon and the species of other 

 genera closely related to it. 



Correlation of Carboniferous beds in 

 America and Europe, or even between 

 different coal fields in either continent, 

 still offers many problems, but a tenta- 



tive correlation may be arrived at which 

 enables us to place the Calhoun material 

 in its approximate position in the time 

 sequence. This is summarized on the 

 chart given in text figure 1. Further 

 information is given in the many papers 

 published in the Proceedings of the 1927 

 and 1935 Heerlen Congresses on Car- 

 boniferous Stratigraphy. 1 Miss Dix's 

 (1937) correlation of English Upper 

 Carboniferous with the standard West- 

 phalian section has been helpful. Hir- 

 mer (1940) has recently summarized in 

 detail the stratigraphic extent of Upper 

 Carboniferous floras in northwestern 

 continental Europe, and Jongmans 

 (1940) has given a useful summary of 

 the British Coal Measures stratigraphy. 

 Wanless' (1939) recent correlation of 

 the Appalachian and Eastern Interior 

 basins is the most satisfactory treatment 

 available dealing with this difficult sub- 

 ject. More recently, stratigraphic classi- 

 fication of the Pennsylvanian system in 

 Illinois has been revised (Weller, 1941). 

 The Caseyville, Tradewater,- Carbon- 

 dale, and McLeansboro beds are now 

 recognized as groups instead of forma- 



^Bxact titles cited under "Heerlen" in the list of 

 references, pp. 38-40 of this report. 



^Use of the term "Pottsville" as applied to beds 

 of Caseyville and Tradewater age has been dis- 

 continued by the Illinois Geological Survey. The 

 Pottsville beds are generally accepted as equiv- 

 alent to the Pocahontas, New River, Kanawha 

 succession in the Appalachian region. 



