. The Canadian naturalist and geologist. Natural history -- Periodicals. 460 Fossils of the Chazy Limestone. plane,—the apical half being gradually turned towards the flat side, so as to constitute a sub-spiral curve. The width at the base of the most perfect specimen collected is sixteen lines, thick- ness nine lines; length along the outer curve four inches, from the apex in straight line to the inner angle at the base fifteen lines, and to the outer angle two inches and three lines. On the convex side the structure is seen to consist of successive .thin laminae at right angles to the length
. The Canadian naturalist and geologist. Natural history -- Periodicals. 460 Fossils of the Chazy Limestone. plane,—the apical half being gradually turned towards the flat side, so as to constitute a sub-spiral curve. The width at the base of the most perfect specimen collected is sixteen lines, thick- ness nine lines; length along the outer curve four inches, from the apex in straight line to the inner angle at the base fifteen lines, and to the outer angle two inches and three lines. On the convex side the structure is seen to consist of successive .thin laminae at right angles to the length, the unequal development of which forms a sort of a squamose and transversely undulated surface. This operculum resembles that of M. Peachii, but it lis larger and more strongly curved. I have seen no perfect spe- cimens. While the differences in the size of the whorls distinguished this species from M. Peachii, its operculum shews at a glance that it cannot be either M. Logani or M. Magna. I have seen no specimens with the shell preserved. In the cast of the interior the inner whorls are quite ventricose, instead of flat, in some of the individuals; but in others, from the same locality, nearly flat. Locality and Formation.—Mingan Islands. Chazy Limestone. Collectors—Sir W. E. Logan, J. Richardson. There are apparently two other species of Maclurea in the Chazy, one of which may be M. Logani and the other M. Magna ; but they require further examination . Cephalofoda (15 species). Orthoceras Shumardi, N. Fig. 36. Fig. 36.—Longitudinal section of 0. Shumardi, shewing the distance of septa and the position of siphuncle. Description.—Elongate, cylindrical, section circular, tapering at the rate of a little more than half a line to the inch, septa rather strongly convex, distant nearly half the diameter; siphuncle about one fifth the whole diameter, and with its centre distant from the. Please note that these images are extracted from scanned page images that may hav
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