286 
cisor 72 is the first functional tooth, it is in all cases provided with a 
small labial toothlet, which is calcified in the 4 older stages. 
Between this tooth and the next functional one there is a gap as 
above and in it there is situated a small toothlet, labial in position 
and sometimes a minute deeper seated one, these are well in front of 
the next large tooth and evidently represent the reduced 3rd incisor 
(<3) in two dentitions. 
The second functional incisor is then 74; this tooth appears to have 
lost all trace of its predecessor. The last functional incisor 75, is back- 
ward, but may occasional shows traces of its labial predecessor. 
The canines both above and below possess minute calcified labial 
predecessors. 
The premolars. 
In the adult only two premolars are present, both above and below, 
and these THomas (18) has identified on comparative grounds as the 
1st and 3r4; that this identification is correct is easily seen on examin- 
ing the development of these teeth. The first premolar is found to 
develop close to the canine, then follows a long diastema in which the 
dental lamina becomes slightly swollen, this being the last trace of the 
lost 224 premolar, behind this is the large 3rd premolar, while posterior 
to this is the other missing tooth, the fourth premolar, this latter tooth 
has however only been recently lost by Dasyurus consequently we 
find it well developed in all the young specimens examined, the appear- 
ance presented being a well developed labially situated bell-shaped 
enamel organ with a calcified tooth often very irregular but sometimes 
of considerable size, this represents the so-called deciduous fourth pre- 
molar, while lingually the dental lamina is much swollen and through 
it probably does not differentiate much further we may safely regard 
this are representing the so-called permanent 4th premolar (ppm 4) or 
as I have elsewhere sought to prove (12) a retarded milk premolar. 
The condition of this deciduous fourth premolar is extremely inter- 
esting and presents a very close resemblance to that of the less re- 
duced among the labial premilk teeth in front, this is especially 
apparent in the youngest stage where the enamel organs of these teeth 
are just appearing, and from the fact that they appear about the same 
time and are similarly situated one might be inclined to refer them 
to one dentition, for LECHE (4, p. 138) states that this is the true 
criterion for determining the teeth belonging to the same set, but with 
this statement I disagree entirely and I doubt if LecaE would still 
insist on this point, for instance in the mole (14) I have shown that 
taking this as a criterion one would have to regard the deciduous in- 
