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 field 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 (f) 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 Pusispira 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. 



