280 Canadian Record of Science. 



appears in Mr. Fletcher's table/ where Mr. Kidston is 

 recorded as referring these beds to the Coal Measures, 

 while I am quoted as correlating them with the Pottsville 

 (Millstone Grit). This difference represents only a varia- 

 tion in the nomenclature of the Coal Measures in Great 

 Britain and in America. The upper portion of the Penn- 

 sylvanian Pottsville appears, as I have elsewhere indicated,^ 

 to be contemporaneous with the Lower Coal Measures of 

 Europe, while the succeeding beds in the northern Appa- 

 lachian area of this country represent the Middle Coal 

 Measures, etc., of the Old World. Accordingly my corre- 

 lation of the fern beds at St. John with the upper Potts- 

 ville nearly corresponds to Mr. Kidston's correlation with 

 the Lower Coal Measures. I do not insist that the 

 Riversdale plants are necessarily so late as the Pottsville, 

 though I believe they belong close to, if not in, the Potts- 

 ville stage. It is interesting to note that the conclusions 

 reached by Mr. Kidston and myself, each independently 

 and without the knowledge of the other, as to the age of 

 the plant beds under discussion, are nearly identical. Not 

 less interesting is it that our conclusions, with the excep- 

 tion of those relating to the St. John fern ledges, tend in 

 general to sustain the correlations made by Sir William 

 Dawson thirty years or more ago. 



So far as I can recollect, I have never seen a fossil from 

 the Union, or expressed an opinion as to the age of that 

 formation, which in Mr. Fletcher's table I am credited as 

 doubtfully referring to the Coal Measures. The terranes 

 referred by Mr. Fletcher to this formation, which from 

 the descriptions seems to have some features in common 

 with the Catskill, do not appear to have yet yielded 

 plant remains of stratigraphical value. 



1 Op. cit., p. 243. See p. 3 of this paper. 



2 Bull. Geol. Soc. America, Vol. XI., pp. 1G6, 173; 20Ui Ann. Kept. U.S. Geul. 

 Snrv., pt. 2, pp. 912, 917. 



