Few horizons in Ontario are of more geological interest than that of the Oriskany sandstone. This is largely because of its abundance of well preserved fossils and the relation which it bears to the preceding and succeeding formations. Apparently, on the authority of Billings, Logan gives a list of thirty species from the Oriskany sandstone2 of North Cayuga township, in which ten are characteristic Oriskany forms, and the remainder are among those usually found in the Onondaga (Corniferous) limestone. About ten years later Nicholson writes, “The fauna of the Oriskany sandstone of Canada is, with very few exceptions, identical with that of the Corniferous (Onondaga) limestone. All the typical and characteristic forms of life in the former pass up into the latter, and it is thus impossible to draw any paleontological line of separation between them.”3 He says further, “I have myself detected no . . .