Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/422

Conodonts were first noticed on the American continent by Dr. Newberry, wbo, in the second volume of the ' Palaeontology of Ohio' (1875), figured several forms and discussed their probable relations, which he believed to be rather with fishes similar to Myxinoids than with invertebrates. All Dr. Newberry's specimens were from the Lower Carboniferous at Bedford in the State of Ohio. The oldest strata in which I have met with Conodonts are thin layers of a dark limestone belonging to the Chazy formation of the Cambro-Silurian, which, if not the equivalents, are not far separate in relative age from the green sands and black shales of Russia, the lowest beds in which theso bodies have been found there. These Chazy beds are exposed on the banks of the Ottawa River at Cren- villc, in the province of Quebec, and are largely composed of the small tests of bivalve Crustaceans belonging to the genus Leperditia, associated with a few small Trilobites and Gasteropods. There are no indications of any of the larger Crustacea or Mollusca to which these Conodonts could be referred ; and they are altogether too large, even if they could be referred to either of these classes of animals, to have belonged to those whose tests are here preserved. Though the Conodonts are not unfrequent in these limestones, it is somewhat remarkable that they are all of one species, and this is one of the largest of the known compound forms. In the strata of the Cincinnati group exposed near Toronto, in which a few Conodonts appear, the rocks are principally micaceous flags and shales, and contain a great variety of fossils, Graptolites, Corals, Annelids, Brachiopods, Gasteropods, and Ccphalopods of the genus Orthooeras, all well-known forms. No crustacean remains beyond scattered fragments of small Trilobites of the genus Caly- mene have been noticed. Whilst most of these fossils are in thin lenticular beds of limestone intervening between the flags and shales, the Conodonts are generally imbedded in the latter. In addition to a few compound teeth, there are also the simple spine-like forms of Conodonts ; and it is worthy of notice that these simple forms are much more restricted in their distribution than the compound ; for whilst the latter appear from the Cambro-Silnrian to the Lower Carboniferous, the simple teeth are only met with, both in America and in Russia, in the Cambro-Silurian. I have not as yet found any Conodonts in the Trenton and Utica shale rocks, which come betweeen the Chazy and the Cincinnati group, nor in any strata of the Silurian proper and the lower division of the Devonian; but in the middle Devonian they reappear in great abundance. In strata of this age belonging to the upper beds of the Hamilton group of limestone and shales, exposed near the village of North Evans, on the south shore of Lake Erie, New York State, they are very numerous ; and one particular band of limestone, which I propose to designate the Conodont-bcd, is filled with fragments of these small teeth. This limestone band varies from half an inch to three inches in thickness, and may be traced for some distance. On fracture it presents a dark subcrystallino aspect, with occasional particles of a green colour, and also crystals of iron-