. The Quarterly journal of the Geological Society of London. ption, isof the left side (figs. 9-12). Its length is six inches 8 lines, itsbreadth 5 inches ; the longitudinal extent of the proximal, or mas- * In Platecarpus curtirostris, pi. xvi. fig. 4, and, again, in Plat, ictericvs,pi. xvii. fig. Op. cit. p. 114. THE REPTILIAN CLASS OF THE MOSASAURIMC. 691 toid surface is 4 inches 2 lines; that of the distal, or mandibular,surface, is 4 inches 3 lines. The proximal articular surface, fig. 11, a, is in great part roughfor close ligamentous or fibro-cartilaginous union with the mastoidand
. The Quarterly journal of the Geological Society of London. ption, isof the left side (figs. 9-12). Its length is six inches 8 lines, itsbreadth 5 inches ; the longitudinal extent of the proximal, or mas- * In Platecarpus curtirostris, pi. xvi. fig. 4, and, again, in Plat, ictericvs,pi. xvii. fig. Op. cit. p. 114. THE REPTILIAN CLASS OF THE MOSASAURIMC. 691 toid surface is 4 inches 2 lines; that of the distal, or mandibular,surface, is 4 inches 3 lines. The proximal articular surface, fig. 11, a, is in great part roughfor close ligamentous or fibro-cartilaginous union with the mastoidand squamosal: it is convex antero-posteriorly, curving downwardand backward, as in Amblyrhynchus, leaving the fore part of theproximal end of the tympanic free and smooth. Transversely therough articular surface, a, is flat or feebly concave. Any swingingmovement of the tympanic seems not to be permitted by this fore part of the tympanic is a broad plate of bone formingthat wall of the large tympanic cavity, fig. 9, c: the margin of Fig. 9. Fig. Outer surface, Inuer surface. Tympanic bone of Mosasaurus Hojpmanni, ^ natural size. 9 and 10, the same bone of Python Sebce. the plate, b, which is turned outwaid (laterad), is deeply grooved,as in Amblyrhynchus, for the attachment of the tympanic cavity, c, is vertically oblong, 5 inches in thatdirection across the outlet, 3 inches transversely across the upperend, and gradually contracting to 1| inch as it descends; itsdepth is 2 inches at the deepest part. The stapedial orifice, d,is at the upper and back part of the cavity, and is of a subellipticform, 9 lines in long diameter. The proximal articular end archesover this aperture to within a line of the substapedial tuberosity, the lower end of the grooved part of the frame the bordercurves backward and upward, with a sbarpish ungrooved marginterminated abruptly by a notch, /, within an inch of the end of theupper arched border contributed by the
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Keywords: ., bookcentury1800, bookdecade1840, bookidquarte, booksubjectgeology
