SUCCESSION OF THE TEETH IN THE DASYURIPLE. 
445 
Premolars. 
Molars. 
Thylacinus. 
3 
4 
Sarcophilus. 
2 
4 
Uasyurus. 
2 
4 
Phascologale. 
3 
(rarely 2 below) 
4 
Smintliopsis* * * § . 
3 
4 
Antechinomys. 
3 
4 
Myrmecobius. 
3 
5 or 6 
Nothing of importance seems to have been published as to the tooth-change in any 
of these genera, with the exception of Thylacinus, worked out by Professor Flower. 
This animal has its successional tooth, or “ pm 4 ,”t preceded by a distinct milk-molar, 
which is, however, never functional, and falls out exceedingly early. 
In Dasyurus and Sarcophilus neither of the two premolars has a milk predecessor, 
and, owing to this, their homologies have not been finally determined, although 
Professor Flower has acutely suggested,^ judging only from Krefft’s description § of 
his “ Chcetocercus cristicauda,” that it is the last, and usually changing, premolar 
which has disappeared, a suggestion which I am now in a position to prove entirely 
true. 
On Sminthopsis and Antechinomys I propose to make no remarks, as their dentition 
is palpably the same as that of the common members of the genus Phascologcde, 
on which my chief observations have been made, and from which I shall afterwards 
return to Dasyurus and the other members of the family. 
In Phascologcde the shape and size of the two anterior permanent premolars are 
always very constant, but the third and last, or pm 4 , presents us with a remarkable series 
of gradations in size, gradations which prove that it is undoubtedly this tooth that has 
altogether disappeared in Dasyurus and Sarcophilus. These gradations do not need 
detailed description here, especially as the figures (Plate 27, figs. 1-5) show them far 
more intelligibly than any description could do. It is sufficient to say that in certain 
species, such as Phascologcde virginice and penicillata (figs. 1 and 2), the tooth is 
larger and longer than pm 3 , and that from this size a perfect set of gradations exists, 
down to the minute and practically functionless tooth found in Ph. apicalis (fig. 4), 
while in two species even, Ph. cristicaudata and thorheclciana, the tooth is often 
altogether absent in the lower jaw. 
* = Podabrus, Gould, auctorum. 
f This tooth, being’ the homologue of the fourth premolar of other Mammals, should evidently be 
called by the same name, viz., pm 4 , whatever the actual number of premolars, and therefore its serial 
position, may be. 
J ‘ Journ. Anat. Physiol.,’ vol 3, p. 277. 
§ ‘ Zool. Soc. Proc.,’ 1860, p. 435. 
