1885.] in Pennsylvania and New York. 645 
collected, This was done, and the results were embodied in the 
volume in question, G, of the Pennsylvania reports. 
In the preface to the volume Professor James Hall, of Albany, 
has, through the State geologist, honored the paleontological 
portion of the work with certain criticisms which call for a few 
remarks. The science of paleontology advances so rapidly that 
statements which were perfectly correct at one time often cease 
to be so, and from this ground, if from no other, the criticisins 
contained in the preface of Professor White’s report require 
some notice. 
L 
It will not be necessary at any length to discuss Professor 
Hall’s first remark concerning the dividing plane between the 
Chemung and the Catskill. In the present state of our know- 
ledge this must be largely a matter of opinion. One observation 
will suffice. Whatever may ‘be the fact in Montour and Colum- 
bia counties, there is no doubt that in Perry county, with which 
the writer is better acquainted, spirifers, unbroken and with both 
valves in contact, are found about 1000 feet above red sandstone 
beds holding the scales of Holoptychius or Bothriolepis or both. 
I, 
In regard to the spirifers of the Chemung, certain statements 
are made which are not in harmony with facts which the writer 
has observed in Middle Pennsylvania. For instance, on page xx 
we read: 
“How is it possible to credit such a topsy-turvy appearance of 
the three species of Spirifera which, outside of mh aise, 
have been found (1) never in any but ‘Chemung roc ocks; (2) co 
fined each to its own horizon; and (3) always ina fixed sage 
from above downward, thus : 
Spir ifera disjuncta horizon (S. dj.). 
Spirifera mesocostalis horizon (S. mc.). 
Spirifera mesostrialis horizon (S. ms.).” 
On page xxi we read further: 
“ Spirifera cin aia and Spirifera mesostrialis form an impossi- 
ble ? conjunction 
This assertion must be, to say the least, somewhat hazardous 
even with the interrogative point. 
Again, on the same page: 
“Professor Hall has never seen any two of the three species 
