HUDSON RIVER BEDS NEAR ALBANY 511 



and geographic relations of the Hudson river shales and Trenton 

 limestone will be discussed more fully at a more opportune occa- 

 sion. 



R. R. Gurley 



Dr R. R. Gurley has, after an exhaustive study of the North 

 American graptolites, prepared a list of their vertical range (50) 

 and, as a result of his investigations, concluded (p. 291) that *^ the 

 vertical range of the American species represents a complete 

 parallel to the range in other countries. This parallel is not a 

 general one only, but is exceedingly detailed, extending beyond 

 the genera down to the species, which in each horizon correspond 

 to those of the equivalent European horizon almost without ex- 

 ception, although of course not every European species occurs in 

 America, or vice versa '\ This inference stands in accord with 

 Lapworth's conclusion of the parallelism of the graptolite faunas 

 and supports his correlation of the Normans kill zone with the 

 lower Trenton on the base of such parallelism. Dr Gurley also 

 asserts the lower Trenton age of this zone, which he terms the 

 Lower Dicellograptus zone.^ 



T. N. Dale 



Shortly after the completion of the present paper a mofit 

 elaborate account of the slate formation in the region to the 

 northeast of the investigated territory, by T. Nelson Dale (63) 

 came to hand. Mr Dale's views in regard to the age of the Hud- 

 son river beds agree in a gratifying manner with the results to 

 which the writer was led by his own observations. In the slate 

 belt, which extends northward from, the Hoosac river in eastern 

 New York and in Vermont for about 55 miles, the Cambrian 

 slates are in some localities followed by Calciferons shales, with 

 Calciferous graptolites and thin limestone beds, but in more lo- 

 calities they are overlaid by various other Champlainic [Lower 

 Siluric] rocks which are described as Hudson grits, Hudson 



^The upper Dicellograptus zone is Lapworth's zone without O o e n o - 

 graptus gracilis, in which, however, subsequently a C o e n o - 

 g r a p t u s has been found by Ami, and which has not yet been clearly 

 differentiated in the Hudson river valley. 



