known with a degree of completeness. During the mid¬ 
dle of the nineteenth century Binney, Carruthers, and 
Williamson began a brilliant period of investigation on 
British coal balls which culminated in the fruitful re¬ 
searches of Scott, Maslen, Benson, and their students. 
Coal balls have been found in England, Holland, 
Belgium, France, Germany, Moravia, Russia, Australia, 
and the United States. They have been reported also in 
China, but so far as I am aware, no plant forms have 
been described from Chinese specimens. 
The first discovery of coal balls in America was an¬ 
nounced nearly twenty years ago when the late Doctor 
A. C. Noe recognized them in Illinois. Subsequently he 
located coal balls in Indiana and Kentucky, and reported 
pyritized nodules from Iowa. Plant remains were ob¬ 
served in all of these, but no comprehensive report on 
their botanical content has ever been published. Noe 
made several contributions to our knowledge of their 
plants in enumerations of species, the number of entries 
increasing rapidly with encouraging variety (1925,1931, 
1931). However, the detailed descriptions he left to his 
students, notably Hoskins, Graham (1934), Reed, Krick, 
and Schopf. Recently Arnold and Steidtmann have also 
made additions to the flora of Illinois coal balls. 
Two years ago, Mr. Frederick Oliver Thompson of 
Des Moines, Iowa, began a diligent search for new oc¬ 
currences of coal balls and his efforts were rewarded by 
their discovery at four localities in the Des Moines Series 
of the Pennsylvanian deposits of Iowa. He has trans¬ 
mitted to the Botanical Museum of Harvard University 
more than 1800 nodules varying in their diameters from 
3 to 22 inches. 
A person unfamiliar with the study of structurally 
preserved fossil plants is frequently unaware of the diffi¬ 
culties which attend the investigation of paleobotanical 
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