Page:Quarterly Journal of the Geological Society of London, vol. 32.djvu/155

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over the residuary, more or less shapeless blocks of matrix from the Karoo lacustrine deposits of South Africa, transmitted by their discoverer the late Andrew Geddes Bain, Esq., F.G.S., I came upon a lump about the size of one's fist, in which the sole indication of organic remains was a pair of mutilated canine-shaped teeth.

Part of the outer enamelled surface was exposed to view, and suggested that the block might contain a fragment of the upper jaw of a Dicynodon. On clearing away the matrix from the teeth, however, they presented a difference of shape from the tusks in that genus: the crown was narrow instead of round; the transverse section was a long oval (Pl. XI. fig. 3) with the small end pointed: when the whole of the outer side of the crown became exposed, the shape of the best-preserved canine (ib. fig. 2) resembled that in Machairodus, and most so that of Machairodus latidens. On carefully relieving the hinder trenchant margin of the tooth from the matrix, I was much interested in finding that it carried the resemblance to the canine of the extinct feline mammal to correspondence in the minute serration of that margin (ib. ib. c').

A small part only of the non-enamelled base was preserved, the canines having been broken off a little above their exit from the socket; but the breadth of the broken base and the reduction of the pulp-cavity to a linear trace were indicative of a long and deeply implanted fang. Nevertheless it was evident that, in proportion to the antero-posterior diameter of the base of the enamelled crown, that part of the tooth was relatively longer than in Machairodus latidens: it differed also in the absence of the serrate border at the fore part of the crown (ib. ib. c). The only part of the skull preserved posterior to that supporting the upper canines was a portion of the lower jaw, of which the alveolar border of the right ramus extended one inch behind the right better-preserved upper canine, No trace of tooth could be detected in this border.

The symphysial part of the lower jaw (fig. 5) extended forward about 2 inches in advance of the upper canines (ib. c. c). The animal had become fossilized with its mouth shut; and the upper canines descended along a laterally compressed part of the lower jaw, also as in Machairodus, one on each side, with their points projecting beyond the lower border of the jaw (fig. 1, c, c). The next thought was as to possible evidences of the teeth at the fore end of the lower jaw; but not until the extremely hard matrix had been ground down to the alveolar border were any such traces visible. The crowns of these teeth seemed to have been broken away prior to interment; but the bases of eight incisors and of two lower canines were exposed, in transverse sections at the level stated.