Rules and Misrules in Classijication. — Marcou. 129 
come patches, and finally when the southern boundary of 
Rensselaer county is reached the Georgia formation takes the 
form of broad bands, extending through the state of Vermont. 
If we compare those Georgian outcrops with the Taconic of 
the map of P^mmons of 1844, we see that the main part of the 
original Taconic between Williamstown (Massachusetts), and 
Albany and Troy (New York), is inclosed in the Georgian. 
The only difference consists in the broadness of the great band 
of Primordial, the map of 1894 reducing the dimension of the 
band on both sides (east and west) so as to frame and involve 
almost totally the Taconic within strata which are called Si- 
lurian. 
Here now comes the delicate and not satisfactory point, for 
whatever may be the opinions or personal inclinations, it is 
difficult to accept as identical, formations differing in every 
way, stratigraphic, lithologij:; and palaeontologic, and with 
thickness absolutely most disproportionate with the standard 
and typical formations close by — being separated by distances 
less than the range of a cannon-ball shot. In order to avoid 
this difficulty Mr, Hall has created two new divisions in the 
Lower Silurian or Champlain system under the names of 
"Metamorphic Trenton and Calciferous" and "Metamorphic 
Hudson River formation." The state geologist, instead of 
preserving distinct the two divisions of the Hudson or Lor- 
raine and Utica, as they are on the maps of 1842 and 1844, 
has united them in a single division called "Hudson River and 
Utica," with the omission of the word '"Lorraine." 
In the legend the position occupied by the two new "meta- 
morphic" divisions is misleading, for the metamorphic Trenton 
and Calciferous is placed between the normal Calciferous and 
the normal Trenton, and the metamorphic Hudson is placed 
between the normal Trenton and the normal Hudson, which 
seems to imply that the metamorphic divisions preceded the 
normal divisions with which they are identified, being, accord- 
ing to the legend, older than their typical and normal forms; 
which would be just the contrary, for if they are truly the 
metamorphic of the divisions they are claimed for, they ought 
to be placed above those divisions and not below, for the 
metamorphism as the word implies came always after the 
deposition of the regular strata and consequently succeeded 
in the chronology of geologic history. 
