1877.] PROF. OWEN ON A NEW SPECIES OF STHENURUs. 359 
course. The condition of d4 in the Kangaroo adds to the cha- 
racters which have led odontologists to regard the three “true 
molars”? of the diphyodont mammals, as being essentially a backward 
continuation of the first or deciduous series of teeth. With respect 
to d2, in Macropus, F. Cuvier remarks! :—« Dans le jeune age, la 
premicre macheliére est mince et analogue aux fausses molaires des 
genres précédens”’ (Halmaturus, Hypsiprymnus). “A mesure que 
les dents postérieures se développent, les antérienres qui sont usées 
et qui sont pouss¢es en avant par les premiéres, s’oblitérent et tom- 
bent de mianitre qu’elles finissent par se réduire A trois. Ainsi les 
premiéres ne sont pas, comme chez les halmatures, remplacées par 
des dents qui se développent sous elles, mais par les dents qui se 
sont développées derriére elles.” 
Now, if this statement of the distinguished odontologist (to whom 
we are indebted for the first work containing figures and formule of 
the teeth of the class Mammalia as then known) had been founded 
on fact, the distinction of Sthenurus from Macropus and its concomi- 
tant resemblance to Dorcopsis would have been as great as Prof. 
Garrod seems to have concluded. The mistake may have arisen 
from F., Cuvier having limited his quest to the part of the jaw imme- 
diately beneath the slender < premiére machelitre ’ (d2, B, in fig. 1). 
But had he carried the investigation further back he would certainly 
have come upon the vertical successor, p 3, of d3, which he so well 
describes as characterizing his (not [lliger’s) genus Halmaturus?. 
This procedure I practised in comparing, for description in the 
‘Appendix’ to Mitchell’s ‘Three Expeditions’ &c., the fossil 
remains from Australia, which that early and distinguished explorer 
of the continent brought to England and submitted to me in 1836 ; 
and thus I became aware of F. Cuvier’s mistaken view of the generic 
character of Macropus, and was led to the discovery of the imma- 
turity of the individual Macropodidz of which portions of the fossi! 
mandible and teeth seemed to represent full-grown Kangaroos of 
larger size than the largest known living Specimen, called on that 
account Macropus major. 
Later investigations of the fossil marsupials of Australia have led 
to the interesting result, that the developmental condition which 
F. Cuvier believed to differentiate the larger Kangaroos of the genus 
Macropus from the smaller kinds referred to Halmaturus and 
Hypsiprymnus does actually differentiate the huge extinct herbivo- 
rous marsupials of the genera Nototherium and Diprotodon from the 
Macropodide, which we now know to have been represented by 
species much exceeding in size the existing Kangaroos. Moreover, 
the large extinct Kangaroos, even in the partial degree in which 
we have already come to know them, manifest much better grounds 
for generic or subgeneric distribution than do any of the existing 
forms. And such extinct genera, represented as they are by species 
1 «Des Dents des Mammiféres,’ 8yo, 1825, p. 138. 
? Op. cit. p. 136. Mr. Waterhouse has given good illustrations of the deci- 
duous and permanent. premolars of Hypsiprymnus, in plate x. figs, 2, 4, of his 
‘Natural History of the Mammalia,’ 8yo0, 1845, p. 104. 
