424 THE CANADIAN NATURALIST. [Vol. vi. 



and G. M. Hall, confirmed by those of Logan, were correct, viz : 

 that the trilobites in question occur not in a system of strata 

 lying unconformably beneath the red sandrock, but in beds inter- 

 calated with the red sandrock itself, it is clear that these trilo- 

 bites must belong not to the Taconic, but to the New York system. 

 We shall return to the question of the age of these rocks. 



We have seen that Prof. James Hall, in 1847, and again in 

 1859, referred trilobites regarded by him as species of Olenus to 

 the Hudson-River group, or in other words to the summit of the 

 second paleozoic founa, while it is now well known that they are 

 characteristic of the first fauna. In this reference, in 1847, Prof. 

 Hall was justified by the singular errors which we have already 

 pointed out in the works of Hisinger on the geology of Scandi- 

 navia. In his AnteeJcningar, in 1828, while the colored map 

 and accompanying sections show the alum-slates with Paradoxides 

 to lie beneath, and the clay-slates with graptolites, above the 

 orthoceratite-limestone, the accompanying colored legend, designed 

 to explain the map and sections, gives these two slates with the 

 numbers 3 and 4, as if they were contiguous and beneath the 

 limestone^ which is numbered 5. The student who, in his per- 

 plexity, turned from this to the later work of Hisinger, his 

 Lethaea Suecica, found the two groups of slates, as before, placed 

 in juxtaposition, but assigned, together, to a position above the 

 orthoceratite-limestone. Thus, in either case, he would be led to 

 the conclusion that in Scandinavia the alum-slates with OJenus^ 

 Paradoxides and Conocejjhdus (Conocoryphe) wer*^ closely asso- 

 ciated with the graptolitic shales ; and, upon the authority of the 

 latter work, that the position of both of these was there above the 

 orthoceratite-limestones, and at the summit of the second fauna. 

 The graptolitic shales of Scandinavia were already identified 

 with those of the Utica and Hudson-River formations of the 

 New York system. The red sandrock of Vermont, containing 

 Conocephalus, had ^een, both by Emmons and Adams, alike on 

 lithological and stratigraphical grounds, referred to the still higher 

 Medina sandstone ; a view which, as we have seen, was still main- 

 tained and strongly defended by Adams. This was in 1847, 

 and Angelin's classification of the transition rocks of Scandinavia, 

 fixing the position of the various trilobitic zones, did not appear 

 until 1854. Prof. Hall had therefore at this time the stronirest 

 reasons for assigning the rocks containing Olenus to the summit 

 of the second fauna. Before we can understand his reasons for 



