SUCCESSION OF THE TEETH IN THE MARSUPIALIA. 
633 
project considerably from the premaxillary bone. The crown of the third, though 
completely calcified, is still retained in its alveolus. The canine has disappeared, but 
its socket is visible, and as this was a macerated skull, it may have been lost acciden- 
tally. The two anterior teeth of the molar series are in place in both jaws, and the 
summit of the third is on a level with the alveolar border. The tip of the lower pro- 
cumbent incisor was free. The germs of the reserve teeth of the molar series were not 
calcified. 
4. In a skull, 5 inches long, belonging to a great Kangaroo {Macropus major), pro- 
bably about half grown (Plate XXIX. fig. 3), the first and second upper incisors are in 
place, the third just appearing beyond the alveolar margin; all traces of the canine and 
its socket have disappeared. The lower incisor projects § inch beyond the front of 
the mandible. The three anterior teeth of the molar series described above, viz. one pre- 
molar and two molars, are in place and in use in both jaws. The crown of a posterior 
molar is just visible in its socket. The crown of the single reserve tooth in each jaw is com- 
pletely calcified, and shows the compressed character of a premolar, having two cusps 
behind and one in front. It is a slightly larger tooth than the premolar which is in place. 
The remaining changes in the dentition of the great Kangaroo have been described so 
fully by Professor Owen that it is unnecessary to follow them here in detail. They 
amount, however, to this — the gradual evolution of the reserve premolar tooth in each 
jaw, which displaces the first tooth having the character of a true molar; the concomi- 
tant shedding of the first premolar ; and the subsequent shedding of the second or reserve 
premolar, followed ultimately by the loss of the two anterior true molars. 
The foregoing observations on the earlier stages of the development of the teeth of 
Macropus are not in accordance with the description of Professor Owen, which runs 
thus. “ The deciduous dentition of the great Kangaroo {Macropus major) is i. 
c. 5 E 5 , d.m. §Ef=18. The canines are rudimental, and are absorbed rather than shed. 
The deciduous incisors are shed before the young animal finally quits the pouch ; when 
this takes place, the dentition is i. \ Ej, d.m. |r|=12, the upper incisors being i. 1 , the 
molars d. 3, and d. 4 of the typical dentition”*. 
I have not been able to find any trace of deciduous incisors in any specimen of Ma- 
cropus examined, and I do not think that if they had advanced to the calcified stage, in 
which alone the term “ shed” would be applicable to their disappearance, they could 
have escaped observation. Further, the analogy with other marsupial genera, presently 
to be shown, gives me greater confidence in the belief that Macropus is, at all events as 
regards the incisors, a monophyodont. 
I am also not disposed to regard the first tooth of the molar series as representing 
one of the deciduous molars of the typical diphyodont dentition ; but the proofs upon 
which this view rests will appear after an examination of the dental succession in other 
genera. 
As the general characters of the teeth of the other members of the family Macropo- 
* Cyclop. Anat. and Phys., Art. “ Teeth,” vol. iv. p. 933. 
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