2o8 The Ottawa Naturalist. [December 



2. Unconformity. 



3. Union fortnatioii, consisting" for the most part of red shales and 



sandstones, &c., as seen in the excellent rock-cuttings along 

 the I. C. R., near Union Station, eight miles below Rivers- 

 dale. 



4. Riversdale Jormation, marked by black carbonaceous, dark grey 



and red, greenish-grey and rusty shales and grey sandstones 

 with a few calcareous layers as seen in the numerous cuttings 

 along: the 1. C. R. east of Riversdale station and in the val- 

 leys of the Calvary Brook and Black River. 



Considerable discussion has arisen of late as to whether the 

 rocks of the Union and Riversdale formations belong to the Car- 

 boniferous or Devonian systems. After describing the two speci- 

 mens obtained by the writer. Prof. Jones and Dr. Woodward make 

 the following statement regarding the horizon at which the genus 

 Bellinurus usually occurs : 



"Although Bellinurus is a very ancient type of Lirnulus, it 

 has not at present been found in rocks of earlier age than the 

 Coal-measures, nor can we assert that the black, grey and glossy 

 shales of Riversdale, Colchester County, Nova Scotia, in which 

 these specimens occur, are older than Carboniferous." 



Several interesting examples of a species of Leaia were found 

 associated with Bellimirus grandcevus in the black shales of the 

 fifth cutting east of Riversdale station which, after examination. 

 Prof. T. R. Jones refers to his Leaia Leidyi. The authors add : 



" Leaia Leidyi, T. R. Jones, which occurs with Bellinurus in 

 these Riversdale black shales, occurs in the Lower Carboniferous 

 of Pennsylvania, but in rocks ' regarded by some geologists as the 

 uppermost part of the Devonian or Old Red Sandstone.'* Leaia 

 also occurs in the Upper Coal Measures of Lancashire and the 

 Lower Carboniferous oi Fifeshire. As the two specimens of Belli- 

 nurus (PI. XV, figs. 2 and 3) are both imperfect, and better 

 materials may at any time be forthcoming, it seems prudent to 

 refrain from suggesting more than one trivial name. This Crus- 

 tacean may therefore be known as Bellinurus grandcevus, Jones 



*" Fossil Estherise," Pal. Soc. Monogr. p. 117, pi. V, figs. 11 and 12. 

 London, 1862. 



