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Show 352 PROF: OWEN ON A NEW SPECIES OF STHENURUS. [Apr. 17, fra On a new Species of Sthenurus, with Remarks on the Relation of the Genus to Dorcopsis, Miiller1. By Professor O W E N , C.B., F.R.S., F.Z.S., &c. [Eeceived April 4, 1877.] (Plates XXXVII. & XXXVIII.) The present species of extinct Kangaroo is founded on a fossil gment of skull including the molar series of both sides of the apper jaw with the intervening bony palate (see Plate XXXVII.). The reference to the genus Sthenurus in Prof. Garrod's excellent memoir on Dorcopsis luctuosus2 encourages m e to think the following notes may not be unacceptable to the Society, which has occasionally admitted illustrations of extinct animals into its publications. The fossil was found in a "rocky alluvial deposit" in the shaft of a gold-lead in the county of Phillip, N e w South Wales, Australia, and was transmitted to me by the Rev. William Branthw-iite Clarke, M.A., F.R.S., the veteran geologist of New South Wales. The fossil is in a massive petrified condition. The genus Sthenurus is chiefly characterized by the configuration and fore-and-aft extent of the premolar (Plate XXXVIII. figs. 1, 5, 12, p 3),which exceeds that of the following molar (ib. figs. 5, 12, d i) commonly to the extent of one half of the next molar, m l. The premolar in the upper jaw has an outer (ib. figs. 3, 7, 14 d) and an inner (ib. ib. e) trenchant plate, the latter being lower in extent, almost basal in position ; the plates are united together by two or more low transverse ridges. The crown of the tooth is thus partly trenchant, partly triturant. The molars have the two transverse lobes (ib. figs. 4, 7, 8, 14, 15, a and b) of the macropodal type, well developed, with their summits trenchant and slightly curved prior to abrasion, with a " prebasal ridge" (ib. figs. 4, 8, 15,/; and a low and small "mid link" (ib. fig. 8, r), continued at almost a right angle forwards from the inner inflection of the fore lobe. The hind lobe of the last molar (m 3) is a little narrower than the fore lobe. The upper incisors (ib. fig. 11) work on the same horizontal plane ; and the crown of the third (i 3) exceeds that of the first (i 1) in fore-and-aft extent. The smallest species of the extinct genus known at the date of my eighth paper on the " Fossil Mammals of Australia " 3 was the type one (Sthenurus atlas) in which the fore-and-aft extent of the crown of the upper premolar (ib. figs. 5, 6, 7, p 3) is 9 lines, that of the entire permanent series of upper molars being 2 inches 11 lines. A second species of Sthenurus (S. brehus) has the upper premolar (ib. figs. 12, 13, 14, p 3) 10 lines in fore-and-aft extent; that of the perma- 1 Zoogd. v. den Indischen Archipel, pt. 4, pl. xxiii. (skull and dentition, figs. 7 and 8), plate xxiv. fig. 7 {Hypsiprymnus brunii; Dorcopsis in text) 1841. 2 Proc. Zool. Soc. 1875, pp. 48 and 58. 3 Phil. Trans. 1874, p. 245, pis. xxii. and xxiv. |