480 W. M. DAVIS AND S. W. LOPER FOSSILIFEROUS TRIASSIC SHALE. 



The most marked features of this comparison are the absence of Ischyp- 

 terus gigas from the anterior shales, where so many other species of fish are 

 found, and the limitation of several species of plants to the anterior shales, 

 although the flora of the posterior shales embraces a number of species com- 

 mon to both. ^ 



Resui.ts. 



The work has, therefore, been not only clearly confirmatory of the theory 

 of a faulted monocline, but it has also secured many fine specimens for the 

 National Museum^ and it has shown that systematic exploration may yet 

 reveal much of interest where it was supposed that but little remained to be 

 discovered. 



Washington, D. C, December, 1890. 



DISCUSSION. 



Professor C. H. Hitchcock: Being greatly interested in the facts of this 

 paper, I desire to ask Professor Davis where, judging from his conclusions as 

 to Connecticut, we should expect to find the fish beds in connection with the 

 Holyoke-Tom range in Massachusetts? 



Professor W. M. Davis: The location of the belts of shale in Massachu- 

 setts will depend on the correlation of the trap ridges of Connecticut and 

 Massachusetts. Without being able at present to settle the question, I am 

 inclined to believe that the anterior sheet in Connecticut, thickens north- 

 ward and becomes the main sheet north of the state line, while the main 

 sheet of Connecticut thins and becomes a subordinate posterior further north- 

 ward. If this is correct we should look for the anterior shales of Connecti- 

 cut on the back of the Mount Tom-Holyoke range ; and the Bear's Hole 

 locality, a mile or two north of the Westfield river, appears to confirm this 

 suggestion. The posterior shales of Connecticut should lie further east, but 

 they are not yet identified. 



Professor B. K. Emerson : Further northward, in Massachusetts, a band 

 of black shale occupies the same horizon above the Holyoke traps, but has 

 furnished only plant remains. In northern Massachusetts the Sunderland 

 and Turners Falls fish beds also occur just above the Deerfield trap sheet. 



