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On Didymodon, a New Genus of Minute Artiodactyle Mammalia, from the Eocene of Vaucluse*

Published online by Cambridge University Press:  17 March 2016

Charles Carter Blake*
Affiliation:
London Institution
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Extract

Since the original foundation of the genus Dichobune by Cuvier, and the critical observations made thereon by Owen, the national collection has continued to receive new accessions, indicating the existence of a certain range of variation in the molars of that genus.

The specimen (No. 30673) in the British Museum collection, is figured in Plate II., by Mr. Mackie. It consists of the three molars of the right side of a species of small quadruped closely resembling Dichobune. The length of the fractured ramus containing these teeth, of which the inner aspect is exposed to the observer, measures 27mm.; its greatest vertical depth between the penultimate and last molar being 11mm.

The last molar (m 3) measures 7mm. in length, and 4 in breadth. Its form is quadricuspid; the two outward cusps being least eroded; from the ectoposterior cusp is developed a slight basal talon, extending towards the entoposterior cusp, which is the smallest of the four, pyramidal, and acuminate; the entoanterior cusp is larger, and is tipped with a small exposed ring of enamel; the ectoanterior cusp is much worn; there is no trace of the distinct hinder lobe of Xiphodon, which lobe in the Dichobune (sp. ?) from Hordwell, marked 29714 in the British Museum, exhibits a well-marked bicuspid division, having the effect of rendering the ultimate molar in that specimen virtually hexacuspid, to a greater extent than in the Dichobune ovina.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1863

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Footnotes

*

From δίδνμος, twofold, and ὀδοῦς, tooth.

References

page 8 note † ‘Ossemens Fossiles,’ vol. v., passim.

page 8 note ‡ Quarterly Journal of the Geological Society, vol. xiii. 1857, p. 254.

page 9 note * This specimen (No. 29714) consists of the last and half the penultimate molars of a Dichobune; the former measuring 14 mm. in length and 8 mm. in breadth. In the specimen marked 29856 the cusps on the posterior lobe arc worn, the breadth as well as the length of the teeth being much smaller than in 29714.

page 10 note * Loc. cit. p. 56.

page 10 note † ‘Geologist,’ vol. v. 1802, p. 32 and p. 124.

page 10 note ‡ Owen, , ‘Quarterly Journal of the Geological Society,” vol. xiii. 1857. pl. iii. fig. 3Google Scholar. The lobe is here marked g.