35^ -^. Winchell on tke Tacontc Question. 
true insight in iS6o, when he wrote: "The upper part of the 
Taconic is equivalent to Barrande's primordial group.'" The 
Cambrian, therefore, \a\d no claim to the chief ground covered 
by the Taconic. 
4. Stratigraph'ical relations of ihc Hjironian of Logan. The 
Huronian system was proposed by Sir W. E. Logan, in 1855, 
for some Canadian strata located north of lake Huron, and sup- 
posed to extend from the base of the Potsdam sandstone down- 
ward to the crystalline schists. His conception was therefore 
identical with that of Dr. Emmons in proposing the Taconic 
system. In the case of the Taconic, strata containing primor- 
dial fossils older than the Potsdam have been found within the 
geographical limits originally assigned to the system. In the 
typical region of the Huronian, no fossiliferous strata have as 
yet been discovered, and it remains to show what part of the 
Taconic they correspond to. In saying this^ I employ Taconic 
as originally conceived by Emmons — a great system extending 
down to the crystalline schists. It may be said, however, as the 
Huronian strata are now known to rest unconformably on lower 
strata which overlie the crystalline schists," so, undoubtedly, 
adequate knowledge of the base of the Taconic, will show the 
inadmissibility of its claim to extend down to the crystalline 
schists. At its base, the Huronian stands, therefore, at the pres- 
ent time, precisely in the position of the Taconic, and is super- 
seded by it. Above, it remains to determine whether the typical 
Huronian reaches up into the zone of the primordial fauna, 
which, as stated, the Taconic includes. In the basin of lake 
Superior, the so-called Kewenian series intervenes between 
schists identified with the Huronian and strata believed to belong 
to the age of the Potsdam sandstone. These hold, therefore, 
the stratigraphical position of the St. Albans, Phillipsburg and 
Swanton groups, with their primordial fauna. As beds having 
an igneous history, they may sustain some such relations to pri- 
mordial life as the poi'phyry of Bohemia, whose eruption ter- 
minated the exitstence of the primordial fauna, before it had 
1 Letter to M.J. Marcou, in The Taconic system and its fosition in strati- 
graphical geology, by Jules INIarcou, Proc. Am. Acad., new ser.,vol. xii, P.1S4. 
2 A. Winchell, in Amer. Jour. Sci., Oct., 18S7, p. ^i^\ American Geologist, 
Jan., 1SS8, pp. 14-24. 
