AGE OF THE GASPE FORMATION 697 



until an intimate acquaintance with the fauna convinced me of what has 

 seemed to me a more trustworthy expression of its relationships. The Hamil- 

 ton element in this composition is not, I should say, ancestral or merely pre- 

 nuncial. We have a striking array of species identical in structure with the 

 Hamilton species of New York. I confess the conception "dominant species," 

 on which the speaker lays much weight, is not to me very imperative. I should 

 say that in this case the dominant species are not so much the survivors from 

 the previous fauna as the Hamiltonian assemblage therein, as the latter is 

 dominant, both in respect to actual individual membership and in percentage of 

 the species as a whole. Some of these sandstone species which had been named 

 by Billings — as, for example, StropJiomena blainvilli and Spirifer gaspensis — 

 may yet prove to be actually identical with Hamilton species, and these, to- 

 gether with certain pelecypods, are dominant rather than the survivors. In the 

 study of these eastern American faunas and those of the South American 

 Devonic I have been alive to the disvaluation in time of certain migrants from 

 earlier faunas, especially Tropidoleptus and Vitulina, and it must be nearly 

 twenty years since I laid some stress on the fact that Tropidoleptus had lost 

 its time value in traveling half way around the world. 



We must not decline to recognize the Hamiltonian assemblage in the Gasp6 

 sandstone merely because this element of the fauna may not be composed of 

 the commoner species which experience usually associates with typical Hamil- 

 ton sections. The crux here is not, "AYhat were the old surviving species doing 

 while the Hamilton species were on their way to this region?" (from the south- 

 west, as I conceive) but, as the speaker has stated, "Are the latter really Ham- 

 iltonian?" As I have described at some length their points of identity with 

 typical Hamilton fossils, I think we must concede that they are, not ancestrally 

 but actually, Hamiltonian, until each identification has been deliberately con- 

 troverted. Granted that the species are competent, the age of the fauna must 

 be interpreted in accordance with the latest age represented by its members. 

 This is the recognized correct procedure. 



It is gratifying that the speaker is in agreement with the conclusion I have 

 drawn, that the northeast basin is an area of dispersion of the Helderberg and 

 Oriskany faunas southwestward. In defining the Grande Greve formation it 

 was pointed out that its lowest limestone beds carried true Oriskany types, 

 great Hipparionyx, Rensselseria, large Leptostrophias, etcetera, and it has also 

 been shown that these species continue upward in the formation, even to its 

 highest beds, all the time becoming more involved in a prevailing Helderber- 

 gian fauna, and with only a few foreshadowings or traces of the Onondaga 

 fauna. Wherever the last element came from, whether on its way out through 

 the Memphremagog passage or on its way in, its representatives are always 

 very primitive in expression. 



There is danger before us in this field in attempting to establish a precise 

 correlation in the eastern region with the faunas of the Appalachian basin of 

 Devonic time. In view of the distances involved and the still obscure paleo- 

 geographic conditions, such ventures should be cautious and restrained. Ap- 

 proximately equivalent expressions are all that can be expected. 



REMARKS BY H. S. WILLIAMS 



In reply to the comments made by Professor Schuchert ; 



1. I am well aware of the difference between the agglomerates (252.1) and 



