ZOIfE OF MISSOURI FLORA IN EUROPEAN COAL FIELDS. 303 



well as the comparative absence of species characteristic of the middle 

 zone of the Valenciennes Basin, indicates for our flora a greater and more 

 significant affinity with that of the beds succeeding the zone of BuUy- 

 Grrenay than with tliose below it; and, if the Old World deposits which are 

 contemporaneous with the Henry County Coal Measures transgress either 

 boundary of the upper zone of the Valenciennes series, the transgression 

 or overlap is undoubtedly on the side of the beds succeeding the Valen- 

 ciennes series and perhaps infringing on the Stephanian. For my own 

 part, I am inclined to consider our flora as perhaps in a measure transi- 

 tional; and that, -^vhile it is probably contemporaneous with a portion at 

 least of the upper zone of the Valenciennes Basin, its marked affinities 

 with many of the types of the Stephanian, as presented in the basins of 

 Commentry or the Saar, make it far from impossible that it may repre- 

 sent a slight paleontologic transgression on the Stephanian ("Houiller 

 superieur"). 



The above conclusions as to the coutemporaneit}- of the Henry County 

 flora with the plants of the upper zone of the Westphalian ("Houiller 

 moyen") in the Franco-Belgian Basin are in striking harmony with the 

 conclusions drawn from our comparisons with the British Coal Measures- 

 For the study of the respective floras by Kidston^ and Zeiller- has shown 

 that the variations of the flora in the different stages of the British series 

 are ver}^ nearly parallel with those in the Valenciennes Basin, so that the 

 Lower Coal Measures of Great Britain are regarded as essentially contem- 

 poraneous with the lower (Vicoigne) zone of the Valenciennes Basin. 

 The Middle Coal Measures are correlated with the middle zone,^ while the 

 transition beds of the British series, the plants of which are less completely 

 known, are referred with little doubt to the zone of Bully-Grenav. Thus we 

 find that those portions of the Old World terranes in (1) the British Coal 

 Measures and (2) the Franco-Belgian Basin, which as the result of entirely 

 independent and distinct paleontologic comparisons I have been led to 

 regard as contemporaneous with our Missouri flora, have, in the course of 

 the paleobotanic studies of the Old World series, been correlated by the 



'Foss. Fl. Eadstock Ser., 1887, p. 408. 

 -Bull. Soe. g(5ol. Fr., (3) vol. xxii, 1895, p. 494. 



3 In the case of the Potteries coal field in North Staffordshire, the uppermost beds are regarded 

 by Zelller, from their paleophytologio characters, as extending a little above the middle zone. 



