6 NEW YORK STATE MUSEUM 



fourth district of the State, and this occurrence was first noted with wood- 

 cuts and names of the fossils in the final report on the geology of that 

 district [1843, p. 137']. As it was evident that the horizon of these few and 

 inconspicuous though significant species (Loxonema boydi, Avicula 

 triquetra, Euomphalus sulcatus, Orthoceras laeve, Atrypa, 

 Delthyris, Cornulites) was above that of the Niagaran fauna, known best 

 then, as now, from its development in the lower beds or Rochester shales, 

 though recognized as continuing into the overlying Lockport limestone, 

 Professor Hall regarded them as appertaining to the life of the Onondaga 

 Salt group — the Salina formation of present usage. A few years later 

 Professor Hall's attention was directed by Sir William Logan to the 

 profuse occurrence of similar fossils in dolomites at Guelph and Gait Ont., 

 and in 1848 he visited these localities, collected freely, and, in 1852, he 

 described and illustrated a considerable number of species obtained by him 

 at that time. 2 In regard to the stratigraphic position of the beds bearing 

 this fauna, he states his view as follows [p. 340] : 



A simple inspection of the plates . . . will show that these fossils 

 are typical of a distinct period from that of the Niagara group, and, though 

 the few species yet known from the base of the Onondaga salt group in 

 New York seem scarcely sufficient to indicate a well marked period or to 

 claim positive identity in age with those of the Gait limestone, yet we are 

 compelled to regard them thus or to rank the latter as a group entirely 

 distinct from any yet recognized. . . Whether we regard them (the Gait 

 and New York fossils) as of the age of the Onondaga Salt group or not, we 

 know that they lie above the strata typified by the numerous fossils already 

 described as belonging to the Niagara group and strictly should form no 

 part of that group. 



This opinion was expressed long before Robert Bell, now acting director 



of the Canadian Geological Survey, proposed to distinguish the formation 



in Ontario by the term Guelph; Hall's term "Gait limestone" being a 



dangerous approach to the better known and older stratigraphic name, 



"Professor Hall, in a subsequent reference to this discovery [N. Y. State Cab. Nat. 

 Hist. 20th an. Rep't. 1868. p. 305 (rev. ed. p. 347)] mentions the origin of the rock 

 exposure, though nothing is said of it in the fourth district report. 



2 Pal. N. Y. 2:341 et seq. 



