420 THE CANADIAN NATURALIST. [Vol. vi. 



latter, according to Emmons) ; thus comprehending both the first 

 and the second paleozoic f\mna ; as shown in the table on page 

 312. 



Emmons, misled by stratigraphical and lithological considera- 

 tions, complicated the question in a singular manner, which 

 scarcely finds a parallel except in the history of Murchison's 

 Silurian sections. Completely inverting, as I have elsewhere 

 shown, the order of succession in his Taconic system, estimated 

 by him at 30,000 feet, he placed near the base of the lower divi- 

 sion of the system the Stockbridge or Eolian limestone, including 

 the white marbles of Vermont; which, by their organic remains, 

 have since been by Billings found to belong to the Levis forma- 

 tion. A large portion of the related rocks in western Vermont 

 and elsewhere, which afibrd a fauna now known to be far more 

 ancient than that of the Lower Taconic just referred to, and as 

 low if not lower than anything in the New York system, were, by 

 Emmons, then placed partly near the summit of the Upper 

 Taconic, and partly not only above the whole Taconic system, 

 but above the Champlain division of the New York system. 

 Thus we find in 1842, in his Report on the Geology of the 

 Northern District of New York (where Emmons defined his 

 views on the Taconic system), that he placed above this latter 

 horizon, both the green sandstone of Sillery near Quebec, and 

 the red sandrock of western Vermont, (which he then regarded as 

 the representatives of the Oneida and the Medina sandstones,) and 

 described the latter as made up from the ruins of Taconic rocks 

 [pages 124, 282]. In 1844-1846, in his Report on the Agri- 

 culture of New York [T. 119], he however adopted a difi"erent 

 view of the red sandrock, assigning it to the Calciferous ; and in 

 1855, in his " American Geology" [ii. 128], it was regarded as 

 in part Calciferous and in part Potsdam. In 1848 Prof. C. B. 

 Adams, then director of the Geological Survey of Vermont, 

 argued strongly against these latter views, and maintained that 

 the red sandrock directly overlaid the shales of the Hudson- 

 River group and corresponded to the Medina and Clinton forma- 

 tions of the New York system. [Amer. Jour. Sci. II, v. 108.] 

 He had before this time discovered in this sandrock, besides 

 what he considered an Atri/pa, abundant remains of a trilobite, 

 which Hall, in 1847, referred to the genus ConocepJialus {Cono- 

 coryphe), remarking at the same time that inasmuch as this 

 genus was (at that time) only described as occurring in 



