SUCCESSION OF THE TEETH IN THE MAKSUPIALIA. 
641 
Postscript, October 31 st, 1867. 
Since the foregoing was sent to the Society I have met with the following observation 
in Waterhouse’s 4 Natural History of the Mammalia,’ vol. ii., Rodentia, 1848, p. 4, foot- 
note : — “ I have sought in vain for deciduous incisors in young Marsupialia ; if they exist 
they must be shed at a very early period in these animals' ’ This important statement 
appears to have passed quite unnoticed by all subsequent writers. 
Burmeister, in his “ Erlauterungen zur Fauna Brasiliens ” (1856), at p. 59, has given 
a somewhat detailed account of the supposed “ milk dentition” of the South American 
Opossums. He describes the teeth of young animals (corresponding in age to that 
shown at Plate XXX. fig. 4), taking it for granted that they are changed as in ordinary 
mammals. 
Description of the Plates. 
The figures are all of the natural size, and drawn from specimens in the Museum of 
the Royal College of Surgeons. The teeth which give place to vertical successors are 
coloured red ; the replacing teeth are blue. Those teeth which neither succeed, nor are 
succeeded by others, are uncoloured. 
PLATE XXIX. 
Figs. 1, 2 & 3. Different stages of the dentition of Macropus , described at pp. 632 & 633. 
Fig. 4. Hypsiprymnus murinus. To show all the true molars in place before the evolu- 
tion of the permanent premolar. 
Figs. 5 & 6. Two stages of the dentition of Phalangista vulpina , described at p. 634. 
PLATE XXX. 
Fig. 1. Immature dentition of Perameles fasciata. 
Fig. 2. Adult dentition of the same animal. 
Figs. 3 & 4. Two stages of immature dentition of Bidelphys , described at pp. 635 & 636. 
Fig. 5. Adult dentition of Bidelphys virginiana , for comparison with the above. 
Fig. 6. Early condition of dentition of Thylacinus cynocephalus. The germ of the first 
upper incisor is concealed by that of the second. 
Fig. 7. Dentition of young Phascolomys vombatus. The premolar is coloured blue, in 
accordance with the conjecture expressed in the description at p. 637, although 
no absolute proof that it replaces another tooth has been given. 
