85 
[Marcou. 
posed these conclusions of Sir William E. Logan, holding that the 
stratigraphical evidence was in favor of regarding the Quebec 
group as middle Silurian, just as Logan had held it.” Op. cit. page 
435 : “ If the Georgia slates are Primordial, then the upper part of 
the Taconic system must be Silurian according to the definition (a 
curious interpretation of Charles H. Hitchcock). Perhaps Prof. 
Emmons will not hesitate to grant this.” “ The latest aspect of 
the controversy rests upon the age of the red sandrock and Georgia 
slates. These were both regarded as middle Silurian by Prof. 
Hall and others. The descriptions of the Oleni (Barrande) from 
the Georgia slates called out M. Barrande’s views, who unequiv- 
ocally pronounced the rocks containing such fossils to be equiva- 
alent to those containing the primordial zone of life in Bohemia, 
that is, to the Potsdam sandstone of America.” This is an erroneous 
interpretation, for M. Barrande never said that the Georgia slates 
were the equivalent of the Potsdam sandstone. 
“ This does not agree with Emmons’ views, for he distinctly 
places the Georgia slates (Taconic slates) unconformably below the 
Potsdam sandstone. Yet M. Barrande supposes that his views will 
support the Taconic system.” 
Yet Mr. Hitchcock says that his “sketch is a more truthful 
expose of the Taconic system of Emmons than the writings of 
Jules Marcou.” Adding “ if one were inclined to be humorous he 
would inquire if it were not possible that Mr. Marcou was trying 
to suppress the Taconic system •” because “ Mr. Marcou makes 
the Potsdam a part of the Taconic ;” saying “ it is my belief that 
he (Emmons) would have abandoned the Taconic system rather 
than have incorporated the Potsdam with it.” If Mr. Hitchcock 
will consult the ‘ Proc. Amer. Acad. Art and Sc.,’ Yol. xii, p. 
189, he will discover in a letter of Emmons addressed to me the 
following remark : “ as it regards the Potsdam sandstone I think 
you are right, so far as Owen’s discoveries are concerned. It is 
a point I have not thought of, and is new to me. The suggestion 
is a good one, and must be met.” 
DATE OF THE PUBLICATION OF THE REPORT OF VERMONT. 
Although the title of the paper of Mr. Hitchcock seems to imply 
that he will give the exact date of publication of the Report of Ver- 
mont, he does not ; but he speaks only of a circular bearing the date 
Jan. 28, 1862. The distribution was not made in Boston until two 
