354 PROF, OWEN ON A NEW SPECIES OF STHENURUS. [Apr. 17, 
in the south-east of New Guinea, with a premolar more trenchant than 
in Sthenurus, and with the proportions of the tooth differing in the 
opposite extreme of fore-and-aft extent, and in greater degree than in 
Halmaturus, from those of the premolar of Sthenurus. This rare 
Kangaroo was deposited in the Zoological Gardens, and on its death, 
in November 1874, was anatomized by the accomplished prosector, 
A. H. Garrod, B.A., by whom the skull and teeth are well described 
and figured’. The state of dentition on both sides of the upper jaw 
is that shown on the left side of the fossil above described; the 
premolar is in place, and the last molar partially extricated from its 
formative alveolus. Prof. Garrod refers the species to the same 
genus as the Dorcopsis muelleri of Schlegel. 
The premolar of Dorcopsis luctuosus shows an antero-posterior ex- 
tent of crown relatively greater than in Sthenurus; it develops a 
single trenchant ridge, forming the main part of the body and sum- 
mit of the crown, being supplemented on the outer and inner sides 
by a subtubercular basal ridge or cingulum. The antero-posterior 
extent of the premolar in the larger kinds of Sthenurus does not 
exceed that of the contiguous molar, d 4, and one half of the next 
molar, m1; in Sthenurus minor (Plate XX XVII. fig. 3, p 3) its ex- 
tent is relatively less; in Dorcopsis it exceeds that of the two suc- 
ceeding molars and a little over (P. Z. S. 1875, plate vii. figs. 2 and 
3). In all the species of Sthenurus the outer ridge of the premolar 
rises directly from the base of the crown (Plate XXXVIII. figs. 1, 
5, 12, p 3), and inclines so little inwards that its summit as well as 
base is on the outer side of the working surface of the tooth (ib. 
figs. 3, 7, 14, p 3, d) ; in Dorcopsis there is a series of small promi- 
nences, a tuberculate cingulum, on the outer side of the base of the 
outer ridge, and the trenchant margin of this ridge (through its 
greater inclination inwards) traverses the middle of the working sur- 
face of the tooth*. The tubercular character of the inner ridge in 
Dorcopsis seems a repetition, on that side, of the tubercular cingulum 
on the outer side of the base of the crown. In Sthenurus the trans- 
verse thickness of the premolar decreases as the crown extends for- 
ward; in Dorcopsis the transverse thickness is uniform, or is main- 
tained to very near both ends of the crown (comp. tom. cit. plate 
vii. fig. 2 with Plate XXXVIII. figs. 3, 7, 14, p 3). 
The broadest (hindmost) part of the premolar in Sthenurus (Plate 
XXXVIII. figs. 7, 14, p 3, ec) is not quite equal to that of the fore 
lobe of the contiguous molar (ib. d 4), and is markedly inferior to 
that of the next (second) molar (Plate XXXVII. fig. 1, m1); in 
Dorcopsis the breadth of the base of the premolar equals that of the 
next and following molars (d 4). 
The post-internal tubercle of the premolar of Sthenurus is united 
by a transverse ridge with the hind summit (Plate XX XVIII. figs. 
6, 7, 13, 14, e) of the outer longitudinal lobe or plate (d). The 
corresponding tubercle in Dorcopsis is not so united with: the homo- 
' P. Z.8. 1875, p. 48, pls. vii., viii., ix. 
2 Hence Prof. Garrod describes the crown of the tooth as “prismatic in 
shape,” loe, cit. p. 54, 
