. The Canadian naturalist and geologist. Natural history -- Periodicals. 438 Fossils of the Chazy Limestone. is broadly convex, except near the beak, where it is narrowly gib- bous and suddenly depressed, to the flat or concave space at the cardinal angles. In many respects this species resembles 0. imperator, but is never more than one-fourth the bulk of that species, and differs from it constantly by the sinus in the front half of the ventral valve. It also occurs in the greatest profusion in localities where the other is not found at all, while in other places the two are asso- ciated. It i
. The Canadian naturalist and geologist. Natural history -- Periodicals. 438 Fossils of the Chazy Limestone. is broadly convex, except near the beak, where it is narrowly gib- bous and suddenly depressed, to the flat or concave space at the cardinal angles. In many respects this species resembles 0. imperator, but is never more than one-fourth the bulk of that species, and differs from it constantly by the sinus in the front half of the ventral valve. It also occurs in the greatest profusion in localities where the other is not found at all, while in other places the two are asso- ciated. It is closely allied to 0. pectinella, but is always much more convex and more numerously ribbed. The width is usually nine lines, length about seven lines; depth of both valves in a very gibbous specimen, six lines. Locality and Formation.—Caughnawaga ; St. Genevieve ; Isle Bizard ; near the village of St. Laurent, and near Cornwall. At Caughnawaga it occurs in vast abundance, but rarely perfect. Chazy limestone. We have several specimens from the Trenton limestone at Ottawa and Belleville which seem to be of this species. Collectors— Sir W. E. Logan, J. Richardson, E. Billings, R» Bell. Orthis platys, (N. s.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Natural History Society of Montreal. Montreal, Dawson
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