322 



molar tooth (m 2), and the complete extrication of the crown of the third 

 upper incisor. 



The dental formula is here, therefore, t ^?, m ^ ; of which the first and second are the 

 deciduous molars ; the third is the first true molar, m 1 ; and the fourth, the second true 

 molar, m 2 : the teeth which are still concealed in the jaws are the premolar, p 4 (the germ 

 of which is exposed on the right side of the upper jaw), and the third and fourth true 

 molars. 



The sutures of the elements of the occipital bone are still unobliterated : the left exocci- 

 pital, the left tympanic, and the right ramus of the mandible are wanting. 



Hunterian. 



1731. The skull of a female Kangaroo (Macropus major). 



The dental formula is, t ^~, m ^^ : but it exhibits a more advanced stage than the pre- 

 ceding. The four molars on the left side of the upper jaw are all of the permanent series, 

 the first being the spurious molar or premolar, the others, the first, second and third true 

 molars. On the right side the second deciduous molar has not been shed, and the premolar 

 is exposed immediately above it. In the lower jaw the deciduous molars are shed on both 

 sides, and the grinders in place are the first, second and third true molars : the premolar had 

 not cut the gum on either side, but is most advanced in the right ramus. This is an in- 

 structive stage of dentition. 



The sutures between the basioccipital and exoccipital are obliterated ; those between the 

 exoccipitals and superoccipital still remain. 



Purchased. 



1732. The skull of a male Kangaroo (Macropus major), showing a corresponding 

 stage of dentition to that of the foregoing specimen. 



The crown of the second deciduous molar, d 4, still remains on the left side of the upper 

 jaw, and that of its successor, the premolar, p 4, is exposed immediately above it. Both have 

 been removed on the right side, showing the socket for the two long roots of the premolar. 

 The crown of the fourth true molar is still sunk in its alveolus. The right ramus of the 

 lower jaw is preserved, showing the premolar, p 4, and the first, second and third true molars 

 in place, and the summits of the crown of the fourth true molar exposed by artificial removal 

 of part of the alveolus. 



Hunterian. 



1733. The skull of a female Kangaroo (Macropus major). 



The premolar, p 4, and the three anterior true molars, are in place on each side of both 

 jaws, and the fourth molar is rather more advanced than in the preceding specimen. The 

 elements of the occipital bone have completely coalesced. 



Hunterian. 



