698 PROCEEDINGS OF THE BALTIMORE MEETING 



the limestone mass (252.2) of the Saint Helens breccias. The two faunas are 

 quite distinct ; that of the limestone is pure Helderbergian ; the other, which I 

 have called the Upper Saint Helens (252.1), contains a distinct fauna. It is 

 this Upper Saint Helens which 1 identify as Oriskanian because of the pres- 

 ence of Spirifer arenosus and Eatonia. In it occur the species having the 

 strongly Hamiltonian aspect. 



2. Regarding the importance of dominant species in determining correlation, 

 I regret that Professor Schuchert can not at present accept the principle. I 

 can only add here that the rare species of a fauna do certainly testify as to 

 its probable connection with another fauna in which the same species are 

 dominant ; but a fauna at large is characterized by its dominant species, and 

 until evidence is furnished as to the time range to which its dominant species 

 are restricted the time relations of the fauna are not established. 



3. I quite agree with Professor Schuchert's view T regarding the Coblenzian 

 significance of the Pelecypods of the York River beds. In my paper I was par- 

 ticularly discussing the correlation with the immediate North American sec- 

 tions. 



4. My conclusion that the fauna should be placed at not higher than the age 

 of the Schoharie of New York is determined chiefly by the absence of charac- 

 teristic Onondagaian species, which have actual representatives in the neigh- 

 boring Chaudiere limestone. 



5. I had not seen Professor Schuchert's paleogeographic charts when the 

 paper was written, and am gratified to know that we are in harmony in inter- 

 preting the geography of this time. / 



6 and 7. Professor Schuchert's differentiation in origin between the Helder- 

 bergian and Oriskanian faunas is quite consistent with my view. In my inter- 

 pretation I had classed the Helderbergian with the Oriskanian faunas, distin- 

 guishing them from the Onondagaian-Hamiltonian faunas. 



I am quite ready to grant that the Helderbergian had its center of distribu- 

 tion farther south than the Oriskanian, but in my grouping them together I 

 referred to the North Atlantic, north of the equator. 



If we adopt Professor Schuchert's location of the Helderbergian in a separate 

 center of distribution farther south than the Oriskanian, I think we have good 

 reason for the early appearance of the Oriskanian fauna at the base of the 

 Grande Greve limestone. 



In reply to Doctor Clarke's remarks, if we ask the question. "Are the species 

 so called really Helderbergian?" we get only an evasive answer. 



Doctor Clarke's claim was that the fauna of the York River beds was equiva- 

 lent in time to the epoch of the Hamilton formation of New York. I do not 

 deny that the species from the York River beds given names of Hamilton 

 species actually possess the specific character of those species. 



My contention is that the paleontologic evidence before us indicates that 

 these "Hamiltonian" species of the York River beds lived and were buried in 

 association with Oriskanian species on the Gaspe peninsula at a time corre- 

 sponding with the Coblenzian of Europe, and probably not later than the 

 Schoharie beds of New York. 



The section adjourned at 12.30 p. m. and met again at 2.15 p, u. with 

 Professor W. B. Clark in the chair. 



