4*V2 \r\v voUK >JTVTr Arisri \f 



Guelph horizon and its fauna in the sections at Rochester and 

 westward. At xUv iiu*eting of the American association for the 

 advanciMueut of science at Rochester in 1893, Prof. Albert L. 

 Arev, then of the Rochester free academy, now of the Brooklyn 

 girls high school, drew the attention of the geologists present 

 to his discovery of a fauna lying in strata at the top of the 

 Ix)ckport dolomite series. These fossils, remarkable for the 

 beauty of their preservation, were obtained by Prof. Arey in 

 nodules of white chert found in the upper dolomite layers at 

 a quarry in the southwest part of the city, then being worked 

 and known as Nellis's quarry, and also from excavations for 

 municipal improvements made in the southern streets of the 

 city. Shortly after this discovery a representative series of 

 thr fossils was submitted to the paleontologist for examina- 

 tion, and it was then proposed that a joint description of this 

 interesting new contribution to our New York faunas should 

 be prepared. Subsequently the fauna was carefully studied 

 by its discoverer and brought into comparison with the charac- 

 teristic Guelph fauna, which is extensively and typically 

 developed in the province of Ontario, and the results of this 

 comparison, which did not extend to the details of specific 

 idt'Utification, were set forth by Prof. Arey on the occasion 

 referred to, and also published in the proceedings of the Roch- 

 ester academv of science, vol. 18. Onlv an inkling of the 

 presence of such a fauna in the New York rocks had before 

 gone on record. As long ago as 1843^ Prof. Hall noted the 

 presence of certain species from what are believed to be the 

 dolomites of this same horizon; and in that report and in his 

 8ul>sequent account of these fossils of the Niagara and Salina 

 rocks in vol. 2 of the Pahontology of Xew York, they were 

 ascribed to the beds of the so called '* Onondaga salt group," the 

 Salina formation of our present nomenclature. Prof. Hall's 

 localities for these fossils were at or near Newark, Wayne co., 

 but we have no other than the original record of them. Ex 

 posures of this upi)er narrow horizon along the summit of the 



MJeol. N. Y. 4th dist. 



