cx THE PALEONTOLOGY OF MINNESOTA. 
in giving the ‘‘ formation and locality” of the species found in them, but the fossils are 
mostly referred simply to the Hudson River formation. 
Now, whatever stratigraphical terms are employed ‘in our provisional efforts to fix the 
horizons of the fossils here described, it is to be understood that the position and range 
assigned to each in the following list is in accordance with our latest and best information. 
Continued investigations in the tield and laboratory have enabled us to correct some errors 
and given us more definite knowledge concerning the geologic and geographic distribution 
of the species. We do not, of course, wish to intimate that the list is in any wise 
permanent or reliable in all parts, yet we are confident that the changes which may be 
necessitated by future discoveries will not materially affect the conclusions which we have 
drawn from the facts brought out by the tables. Now and then the vertical range of a 
species may be extended, but such defections will be more than equalized by the new 
discoveries that are continually rewarding the efforts of the collector. 
The geologic position and range of each species found in Minnesota is indicated by 
the letter x in one or more columns. Species occurring in the upper Mississippi province, 
but not yet discovered within the limits of the state of Minnesota, are distinguished in the 
columns by a dagger (ft) instead of by the letter x. The number of these might have been 
largely increased but it was thought sufficient for our purpose to include only those which 
we may reasonably expect to find in the state. 
In the column devoted to the Fusispira and Nematopora beds, those species which are 
restricted to the latter division are indicated by the letter n instead of by the letter x. The 
letter f in the Phylloporina and Fucoid beds’ column distinguishes the few forms that 
are particularly characteristic of the Fucoid bed. 
Finally, in the columns showing occurrence of species in other regions, the following 
abbreviations are used: Cincinnati region, R for Richmond group, L for Lorraine group, 
U for Utica group, T for Trenton group, B for Black River group, and S for Stones River 
group; Central Tennessee, T for Trenton group (Nashville group of Safford), B for Black 
River group (Carter’s Creek limestone), S for Stones River group (Glade, Ridley, Pierce 
and Central limestones of Safford); New York and Canada, H for Hudson River group, U 
for Utica group, T for Trenton group, B and S for Black River and Stones River or 
Birdseye limestone, and C for Chazy group. In Canada the Black River and Birdseye 
are not separated, hence, in this column the letter B stands for either one or both. 
