. The Canadian journal of science, literature and history. NOTES ON THE FOSSILS OF ONTARIO. 143 large, three rows occupying the width of the stem, the apertures oval, about four in the space of one line measured longitudinally, and six in the same space measured transversely. The cells are arranged in longitudinal alternating rows, and their apertures are surrounded by thick but not elevated margins. The rows of cells are not separated by elevated lines; there are certainly no non-celluliferous, striated marginal zones or borders to the frond, and there is no evidence as to the existence of a
. The Canadian journal of science, literature and history. NOTES ON THE FOSSILS OF ONTARIO. 143 large, three rows occupying the width of the stem, the apertures oval, about four in the space of one line measured longitudinally, and six in the same space measured transversely. The cells are arranged in longitudinal alternating rows, and their apertures are surrounded by thick but not elevated margins. The rows of cells are not separated by elevated lines; there are certainly no non-celluliferous, striated marginal zones or borders to the frond, and there is no evidence as to the existence of a central laminar axis. It is thus more than doubtful if the species can be referred to Ptilodictya; but in the ab- sence of any certain knowledge as to its internal structure, its generic affinities must remain uncertain. Locality and Formation.—Rare in the Clinton Group at Dundas. 17. Fenestella tenuis, Hall. {Ref. Pal. N. Y. Vol. II. pi. xix. 5a-c.) Fragments of this species are not uncommon in the Clinton group at Dundas, but they are ill-preserved, and their more minvite characters can not be made out. 18. Ptilodictya punctata, Nicholson and Hinde. Polyzoary forming a thin flattened expansion, or explanate frond, which probably had a circular fcrm when perfect. Cells arranged in sub-alternate rows, separated by elevated thread-like ridges, which are curved in such a manner as to lead to the belief that the rows of cells were concen- trically disposed of round a central point. Mouths of the cells nearly circular, fiom seven to eight in the space of one line measured across the rows, and about five in the same space measured longitudinally or in the direction of the rows. The cells are separated in a longitudinal direction by well marked spaces, which are occupied by from three to six minute rounded pores, the apertures of as many small cells. No such pores are to be detected on the longitudinal ridges which separate the rows of cells, or on the lateral aspects of Pig
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