356 PROF. OWEN ON A NEW SPECIES OF STHENURUS. | Apr. 17, 
What evidence, it may be asked, does the skeleton afford of the 
affinities of the huge extinct Kangaroos of the genus Sthenurus? I 
am able only to adduce those yielded by the skull. The time may 
arrive when, in some Australian cavern, a greater proportion of the 
enduring framework may be recovered in connexion with the skull 
and dentition of one and the same individual. Fortunately the 
cranial characters at present known are instructive ones, are well 
shown in the portion of skull of the smaller species under description, 
and the more welcome as repeating those previously given by a cor- 
responding portion of askull of Sthenurus brehus (Phil. Trans. 1874, 
plate xxviii. fig. 6). The first of these characters is the integrity of 
the bony palate. In Dorcopsis (P. Z.S. 1875, plate vii. fig. 2), as 
in the Hypsiprymnine, and as in most of the smaller Kangaroos 
which have been grouped under the less-definite genera Halmaturus, 
Petrogale, Lagorchestes, the bony palate shows two or more large 
vacuities’. In Dendrolagus the palate is entire, as in Macropus and 
Sthenurus. The masseteric process is short in Dorcopsis, as in the 
Hypsiprymnines ; it is long in Sthenurus, as in Maeropus. 
The relative position of the masseteric process to particular molar 
teeth, outside which it descends, varies at different phases of the ac- 
quisition of the molars. In Sthenurus it is always opposite the 
interspace between the penultimate and last molar ‘in place.” 
Thus in the immature specimen of Sthenurus minor, in which m3 is 
not extricated, the process is opposite the interspace between m 2 
and mi; in the mature Sthenurus brehus? it is opposite the interspace 
between m2and m3. In the specimen with m3 in place, but less 
mature in age*, the process is opposite a larger proportion of m 2, 
though partly hiding the interspace between it and m3. The rela- 
tive position of the masseteric process, described as a differential 
charaeter between Dorcopsis luctuosa and D, muelleri*, may depend 
upon the incomplete development of m3 in the subject of Prof. Gar- 
rod’s plate vii. fig. 3 (loc. cit.). 
The forward movement of the molar series is effected by that of 
their sockets ; but the superincumbent pier of the zygoma does not 
participate in the molecular additions and subtractions to which that 
movement of the dental cases is due. Such movement is most 
striking, and was first impressed upon my mind as the true dynamic 
in the change of place of growing teeth, in the jaws of the Elephant, 
' The characters of the bony palate are defined and exemplified in the plates 
of the papers “On the Osteology of the Marsupialia,” in the Trans. Zool. Soe, 
In vol. ii. pl. lxxi. fig. 5, the vacuities are shown in Halmaturus bennettii (a near 
ally, if not a local variety of Halm. ruficollis, Gould) ; in vol. ix. pl. Lxxiv. the 
entire condition of the palate is shown in Macropus ( Osphranter) rufus, 
2 “Researches on the Extinct Mammals of Australia,’ 4to, 1877, vol. ii. 
pl. Ixxxviii. fig. 6. 
® Ibid. pl. eviii. figs. 1, 21. 
* «Tn D. luctuosa the apex of the ‘angular process which is developed down- 
wards from the inferior margin of the maxillary portion of the zygoma’ is op- 
posite the anterior cusp of the third molar tooth, whilst in D. mueller? it corre- 
sponds to the posterior cusp of the second molar” (p. 52). In the specimen, 
a8 in the ‘plate vii.,’ the tip of the masseterie process is opposite the interspace 
between the two lobes of m 1. 
