Marcou.] 
58 
[Nov. 7, 
the name Taconic by his superior and not knowing exactly what 
to do, he extended considerably and out of all safe proportions the 
Potsdam formation, placing in it two-thirds of the Taconic sys- 
tem. As regards the Upper Taconic or Supraprimordial fauna, 
Billings was constantly in error. However, he goes so far as to 
admit that the “ physical evidence” is against his classification at 
least for the Calciferous and Levis, and he records the important 
fact that “ the localities in Canada where organic remains abound 
(in the Levis formation), are of limited extent, and widely sepa- 
rated from each other, although they occur in the same line of out- 
crops admitting the sporadic character of that fauna and its 
special apparition so different from any fauna yet known in the 
world, except the colonies described by Barrande in Bohemia. 
Billings in all his palaeontological works has too often referred 
groups of strata to the Potsdam, Calciferous, Chazy and Trenton, 
on very slight indications of similarity of fossil forms, and he 
had included under those names all the Georgia group, the Phii- 
lipsburgh and Levis group, and the Swanton and Citadel Hill of 
Quebec, which are six and seven thousand feet thick, with all their 
colonies and centre of apparitions of the second fauna forms which 
is so characteristic of the upper part of the Taconic system in 
Canada and the United States. 
billings’ classification of 1866. 
In November, 1866, Billings gave another palaeontological clas- 
sification on p. 81 of his “ Catalogues of the Silurian Fossils of the 
Island of Anticosti.” 
FORMATIONS. SYSTEM. 
Chazy. ) 
Break 
Sillery. 
Lauzon (in writing on my copy). 
L6vis. 
Break y Lower Silurian. 
Upper Calciferous (Newfoundland). 
Lower Calciferous (Philipsburgh). 
Upper Potsdam (Wisconsin). 
Lower Potsdam (Georgia, Vt.). 
St. John Group (New Brunswick.) J 
Billings makes a great break between the Levis and Calciferous 
below, and another great break between the Levis and the Chazy 
