PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
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1 line, the breadth of the palate at the prepalatal foramina is 1 inch 9 lines. These 
foramina are elongate, from 2 to 3 lines broad, about 6 lines long, and continued forward 
by a groove (ib. h), which shallows out when parallel with the third incisors. These are 
much worn ; the working-surface of the third is 7 millims. by 6 millims. The enamel, 
which is continued from the outer upon the hinder surface, is impressed, as in the less- 
worn tooth of the younger Brehus , by a longitudinal groove almost equally bisecting the 
outer surface. The second or mid incisor is worn almost to the stump. The first pair 
of incisors, being more worn than in the subject of figure 4, show a working surface 
of similar shape but .rather smaller dimensions ; the anterior coat of enamel is reduced 
to a length of 4 lines (10 millims.). 
In the collection of Marsupial fossils from Queensland in the Museum of the Natural- 
History Society at Worcester, I noted, in 1858, the left lower incisor of a Kangaroo, of 
which I made drawings of the under or outer side (Plate 28. fig. 4). This tooth best agrees 
with the corresponding incisor of Sthenurus Brehus. It had preserved an extent of 
enamelled crown of 8 lines, the breadth being that of the more worn incisor of Plate 28. 
fig. 5. In the large existing Kangaroo {Macropus major*) the breadth of the crown 
of the lower incisor is 4\ lines, in Macropus ( Ospliranter ) rufus it is barely 4 lines. 
The portion of skull of a Sthenurus Atlas (Plate 25. fig. 2, Plate 26. fig. 4) permits 
comparison to be made of the first and third incisors with those teeth in Sthenurus 
Brehus. The first incisor is but half the size of that in the larger species, while the 
third incisor presents a crown of equal size. The generic character of equal division of 
the crown by the longitudinal groove is retained, but the anterior border of the groove 
is produced at the lower part of the crown. Such character, however, may have 
existed in the part of the crown worn away in the subject of Plate 28. fig. 1, is. But 
the difference of proportion in the upper incisors is, at least, specific. In Macropus 
Titan (Plate 25. fig. 4) the modification of the pattern of the third incisor is associated 
with generic distinction in other parts of the dental system and in the skull itself. 
§ 12. Macropus affinis (Metatarsus). — The hind foot in Macropodidce exhibits an 
extreme modification of its bony structure. The inner toe (i) is suppressed ; the meta- 
tarsals of ii & hi are long and filamentary, supporting a pair of small pendent fur- 
cleansing claw-toes ; that of iv is both long and large, with characteristic modifications 
of its proximal end ; that of v is much less, the shaft compressed, but supporting, like 
that of iv, a toe with a quasi hoof for station and progression. 
In Plate 29. fig. 4 is given a view of the fourth and fifth metatarsals, natural size, of 
the right hind foot of the large male Macropus ( Ospliranter ) rufus, already referred to. 
Two other views of the same bone will be found in the paper “ On the Osteology of 
the Marsupialia” in the Zoological Transactions f. 
In the task of determining the fossil specimens of the homologous bones, those best 
agreeing in proportions with the corresponding metatarsals of existing Kangaroos were 
set apart from the fossils deviating in a marked degree from such proportions. 
* Phil. Trans. 1874, plate xx. fig. 15. f Vol. ix. plate Ixx xiii. 
