680 SCHUCHERT ANL> TWENHOFEL ORDOVICIC-SILURIC SECTION 



thonght filled the time of the iinfossiliferous Oneida conglomerate and 

 the Medina sandstone] . . . furnish ns with the materials for con- 

 necting the Hudson Eiver group with the Clinton, by beds of passage 

 containing some of the characteristic fossils of both formations, asso- 

 ciated with many species which do not occur in either." We now know 

 that the Oneida is another phase of the upper or marine Medina/ and it 

 is still true that these formations have yielded in New York as yet but a 

 very meager fauna. On later pages it will be shown that the Medina at 

 Hamilton, Ontario, yields a small "Clinton'' fauna, and that by com- 

 bining all that is known in regard to this formation it appears probable, 

 that this time equivalent is represented by the lower middle part of 

 Division D on Anticosti. In any event, it is true that the Anticosti 

 strata represent a longer and less broken series of marine deposits bridg- 

 ing the time between the latest Ordovicic, or rather the Cincinnatic, and 

 the earliest Siluric than those at any other place in North America. 



It will also be seen that the "Anticosti group" of Billings embraces the 

 stratigraphic equivalent of the "Niagara period" as defined by Dana^ — 

 that is, the Oneida and Medina, the Clinton group, and the Niagara shale 

 and limestone. This usage by Dana was an extension of the term 

 "Niagara group" proposed by the New York State Geologists in 1843, 

 at which time it embraced only what is now known as the Eochester 

 shale and Lockport dolomite. To the Medina, Clinton, and Niagara 

 group the term "Ontario division" was applied by the latter. Clarke 

 and Schuchert^ used Ontario in the sense of a period or system, and 

 accepted the delimitation of it as given by Emmons (1842), who added 

 to the formations mentioned above the Salina and Waterlime — that is, in 

 modern terms, the Cayugan series of Clarke and Schuchert. 



At present we know of no time break in the Divisions D and E of 

 Anticosti; the break, if any, occurs between C and D. Divisions A, B, 

 and the greater part of C have the Cincinnatic faunas, while the life of 

 D and E becomes more and more like that of the Clinton of New York. 

 The strata of Division F, petrologically, are markedly different from 

 those of the other divisions, and the fauna, although not so well known by 

 reason of poor preservation, gives every evidence of being younger than 

 any Clinton biota. Eestricting the term "Anticosti group" of Billings 

 to Divisions D, E, and F, therefore, gives to it strata embracing the same 

 geologic time as that covered by the Niagara period of Dana. Billings's 

 term is of 1857. If restricted as above indicated, it will date from the 



* Hartnagel : New York State Museum, Bulletin 107, 1906, extract 5-7. 



5 Dana : Manual of Geology, first edition, 1863, p. 229 ; fourth edition, 1895, p. 535. 



« Clarke and Schuchert : Science, December 15, 1899, p. 875. 



