357 
THE LOWER AND MIDDLE TACONIC OF EUROPE AND 
NORTH AMERICA. 
By Jui.KS Marcou, Cambridge. 
I. 
Introduction. — The conclusions of my paper : "The Taconic 
system and its position in stratigraphic geology," {Proceed. 
Amer. Acad- Arts and Sciences, new series, vol. xii, p. 255, 
Cambridge, 1885), are that the Taconic system comprehends 
all the strata in which the primordial faunas are found. These 
faunas are three in number. The Infra-Primordial or Lower 
Taconic, the Primordial or Middle Taconic, and the Supra- 
Primordial or Upper Taconic. In the same paper, at p. 224, 
there is a ''Tabular view of the Taconic system in eastern 
North America," in which I have tried to classify in a single 
column the Taconic series of the lake Champlain region (Ver- 
mont, Canada and New York) and of the extreme borders of 
the Atlantic (Newfoundland, New Brunswick and Braintree). 
It is condensed below as follows : 
Snnra- (Potsdam group. 
piipr'd_ 4 Swanton slates. 
l^nmoraial. (phiHipsburgh or Pointe Levis group. 
(Georgia slates or Olenellus (ElliptocepJialus) zone. 
Primordial. - St. John or Acadian group. ) Paradoxides 
( Argillitesof Braintreeand St. Mary's bay. i' zone. 
Infra- ^Eophytoii sandstone of Great Bell Island. land.] 
Primordial. (Aspidella and ylremcoZiifs slates of St. John's. [Newfound 
Four years later I called the attention of observers to the 
existence of "an uninterrupted sea" extending from Scandi- 
navia to eastern Newfoimdland, and that "during the Taconic 
time, an arctic continent existed from the Scandinavian Alps 
to Scotland, Greenland and Labrador, and was united with an 
equatorial continent by a narrow region, somewhat similar to 
the isthmus of Darien or Panama, which connects the conti- 
nent of North America with the continent of South America. 
That Taconic isthmus formed the barrier between the Atlantic 
and Pacific oceans of that remote period of our globe," ("Can- 
adian geological classification for the province of Quebec," 
extra from Proceed. Boston Soc Nat. Hist., vol. xxiv. pp. 75 
and 76, Salem, 1889). 
I propose now to show more plainlj' the existence of those 
two oceans, limiting each one to a special region, sufficiently 
explored so as to allow a great separation between the Taconic 
series ; and at the same time to give a more complete tabular 
view of the strata whicli were deposited in the Acadio-Russian 
