. Second contribution to the studies on the Cambrian faunas of North America [microform]. Paleontology; Arthropoda, Fossil; Arthropoda, Fossil; Paléontologie; Arthropodes fossiles; Arthropodes fossiles. m^A iiii ll? Ml .-' I, m CAMBRIAN FAUNAS OF NORTH AMERICA. J 98. Not having 8tratigrai)Uic ovidotuie of the relation of the GeorKia or Middle Cambrian fauna and tlie ParadoxideH or Lower Caniluiun , other than that tliey occur in the same area and are not in the same stratum of rock, we turn to the fauna to aid in tlie settlement ol' the question. Of the 32 genera of the America
. Second contribution to the studies on the Cambrian faunas of North America [microform]. Paleontology; Arthropoda, Fossil; Arthropoda, Fossil; Paléontologie; Arthropodes fossiles; Arthropodes fossiles. m^A iiii ll? Ml .-' I, m CAMBRIAN FAUNAS OF NORTH AMERICA. J 98. Not having 8tratigrai)Uic ovidotuie of the relation of the GeorKia or Middle Cambrian fauna and tlie ParadoxideH or Lower Caniluiun , other than that tliey occur in the same area and are not in the same stratum of rock, we turn to the fauna to aid in tlie settlement ol' the question. Of the 32 genera of the American Paradoxidcs horizon, 15 pass up into the Oleuellus horizon, viz : Arenicolites, Protospoiigia, Archicocy ttthusT, Eocystites??, Lingulella, Acrotreta,Acrotliele, Kiitorjjina,Ortliis, Stenotheca, Flyolithea, Agnostus, MicrodiscuH, Solenoplcura, andPtyclio paria. Of these, Arenicolites, Protost>ongia, Lingiilclla, Kutorfjina, Acrotreta, Orthis, Hyolithes, Stenotheca, Agnostus, MicTodiscus ?, and Ptyohopariacontinueon up into the Potsdam orUpper Cambrian horizon, leaving but four genera that are common to the Middle antl Lower Cam- brian horizons. One genus, Dendro^raptus, is doubtfully identified in the Paradoxides horizon of New Brunswick, and occurs in the Ui)i)er Cambrian, but is, as yet. unknown in the Middle Cambrian. The geiins Agraulos is also found m tlie Lower and Upper, but not in the Middle Cambrian. Of species, not one of the Gl of the Ameiictan Lower Cam briau fauna are known to occur in the Middle Cambrian fauna, whicii, with its 107 spcicies, stands out clearly from the older fauna and also from the more rectit Potsdam fauna, as but 3 of its species, iVo/« apongiafcnestrata, Stenotheca. eUmgata, and Acrotreta gemma, are known to be common to them ; and ^.0 of the genera in the Middle Cambriiui are not known to i)ass up into the Potsdam or into the Lower Silurian (Ordovician) fauna. Not one species is known to be ctmimon to tlic Lower and Uj)per Cambrian hori
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Keywords: ., bookcentury1800, bookdecade1880, bookpub, booksubjectpaleontology
