173 



referable to the same freological horizon with the great mass of 

 plant and coal-bearing rocks comprised in the Vespertine series, 

 which, as we have seen, lie immediately beneath the gypsiferous 

 marls and carboniferous limestone of southwestern Virginia. 

 The red marl and limestone of the gypsiferous group in Nova 

 Scotia and New Brunswick, with those alternations of red and 

 variegated shales and sandstones which are seen overlying tliem 

 on so grand a scale in the section of the South Joggins, obviously 

 occupy the same geological place as the analogous Umbral series 

 of the Appalachian formations. In both regions we see the lower 

 carbonaceous strata, the accumulation of extensive swamps and 

 estuaries, succeeded by a vast series of marine formations, in the 

 shape of red and variegated marls and shales and beds of lime- 

 stone, thronged with remains characterizing the carboniferous 

 period ; and in both, as we approach the upper limit, we see alter- 

 nations of shales and sandstones with plants and occasional films' 

 of coal, marking the fluctuating dawn of those physical conditions 

 which were to culminate in the vast vegetable deposits of the coal 

 measures. 



Prof. Agassiz inquired what proof there was that the carbon- 

 iferous series so-called is a single formation. As an instance of 

 the manner in which the extension downward of a geological 

 series had been made, he instanced tHe Jura, which twenty years 

 ago was considered a single formation, but which is now divided 

 into seven or nine distinct formations, each with its characteristic 

 fossils. 



Prof. Rogers replied that he used the term " carboniferous 

 series " as a convenient expression for a group of formations of a 

 certain geological period, without imj)lying that it was a single 

 formation ; indeed, he and his brother had long since made a triple 

 division of the series, giving to each division a separate name. 



Prof. Wyman alluded to the idea of Prof. Lyell, that if the 

 trees of this period were hollow, the remains of animals might 

 occasionally be dropped in ; and such remains were actually 

 found and described by him a few years ago. Since then, Prof. 

 Dawson had examined further, and had found remains of an 

 articulate like Julus, and more bones of reptiles, viz : of eight 



