408 MR ROBERT KIDSTON ON THE FOSSIL FLORA OF THE 



A summary of the results brought out by these columns shows that, of the 



98 species occurring in the Eadstock Series — 



55 are common to the Coal Measures of France (excluding the Houiller infdrieur)* 



30 „ „ Zwickau Coal Field. 



24 



30 



9 



17 

 10 

 22 



Lower Saarbriick Series. 

 Middle 

 b Upper „ 



Lower Ottweiler Series. 



„ I Middle 

 „ [ Upper 



The Radstock Series belong to the uppermost beds of the British Coal 

 Measures, with which perhaps the Zwickau Beds are homotaxial. Although 

 the middle division of the Saarbriick Beds contains as many as thirty species in 

 common with the Eadstock Series, the floras of the Saarbriick and Ottweiler 

 Series, taken as a whole, indicate a somewhat higher horizon than that of the 

 Radstock Beds. 



A characteristic Permian conifer, Walchia pinifonnis, Schl., sp., has been 

 observed in the Middle Saarbriick Series, and it also probably occurs in the Ott- 

 weiler Beds. No evidence of this genus has been found in the Radstock Series. 



It is, however, interesting to observe that in the Upper Ottweiler Series 

 (which overlie the Saarbriick Series) no fewer than twenty species occur that 

 are also found in the Radstock Series. Beds of the same age as the Radstock 

 Series appear to be absent from France. Their position is evidently between 

 the Upper and Middle Coal Measures of the French Coal Fields. For the 

 comparative list of the French Superior and Middle Coal Measure plants 

 (Column II.) I am indebted to M. Zeiller, who has spared no trouble in pro- 

 viding me with the desired information. To elucidate this point more fully, 

 I give some extracts from his letters on this interesting subject. 



"Your list (Column I.) seems to me to indicate exactly the passage from the 

 Middle Coal Measures to the Upper Coal Measures, something like the highest 

 zone of the Saarbriick Beds of Weiss, or the base of the Coal Field of Saxony. 

 You will see in my text of the Coal Field of Valenciennes (when it appears, 

 which will not be so soon as I would wish t) what I say on this classification. 



* It may be well to note here the probable equivalents of the French and British Carboniferous 

 Rocks : — 



France. Britain. 



Upper Coal Measures (Houiller Superieur and \ 



Superieur inferieur) . . . J Absent. 



Absent ....... Radstock Series ( = Upper Coal Measures of Britain). 



Middle Coal Measures (Houiller Moyen) . i Middl ° Coal Measure «- 



I Lower Coal Measures. 



Inferior Coal Measures (Houiller inferieur) . Lower Carboniferous { Carboniferous Limestone Series, 

 j. -i-i. a ,i t ™ 1 Calciferous Sandstone Series, 



t lne Atlas of Plates only has been issued. 



