in this as in all other Marsupials have two roots ; their crown
presents a simple compressed conical form, with a posterior tubercle
which is most developed on the hindmost. The true molars {mj in
the upper jaw are unequally triangular, the last being much smaller
than the rest ; the exterior part of the crown is raised into one
large pointed middle cusp and two lateral smaller cusps obscurely
developed ; a small strong obtuse cusp projects from the inner side
of the crown. The molars of the lower jaw are compressed, tri-
cuspidate, the middle cusp being the longest, especially in the two
last molars, which resemble closely the sectorial teeth (dents carnassières)
of the dog and cat.
The dental formula of the genus Dasyurus, is :
Incisors ; canines ^ ; premolars V ; molars ^ : — 42.
The eight incisors of the upper jaw are of the same length
and simple structure, and are arranged in a regular semicircle
without any medium interval. The six incisors of the lower jaw
are similarly arranged, but have thicker crowns than the upper
ones. The canines present the same or even a greater relative
development than in the Thylacine : in an extinct species of
Dasyurus(l) they had the same form and relative proportions as in
the Leopard. The spurious molars (p) have a pointed compressed
triangular crown with a rudimental tubercle at the anterior and posterior
part of its base. The grinding surface of the true molars (m)
in the upper jaw is triangular ; the first presents four sharp cusps, the
second and third each five ; the fourth, which is the smallest, only
three. In the lower jaw the last molar is nearly of equal size with
the penultimate one, and is bristled with four cusps, the external one
being the longest : the second and third molars have five cusps, three
on the inner and two on the outer side ; the first molar has four cusps :
these are all sharply pointed in the young animal, in which the
posterior tubercle of the posterior molar in the lower jaw is divided
into two small cusps.
The carnivorous character of the above dentition is most strongly 1
(1) Dasyurus laniarius : the fossil remains of this species were discovered with those of
two gigantic species of Kangaroo in the bone-caves of Wellington Valley, by Major, now Lieut.-
Col. Sir Thomas L. Mitchell.
marked in the Ursine Dasyure or Devil of the Tasmanian Colonists,
the largest existing species of the genus, and the dentition of which
is represented in PI. 98, fig. 2.
In some of the smaller species of the carnivorous group, as
the Phascogales, the canines lose their great relative size, and the
molar teeth present a surface more cuspidated than sectorial: there
is also an increased number of teeth, and as a consequence of
their equable development they have fewer and shorter interspaces.
Thus the Phascogale penicillata may be said, in Hunter’s words
to have “ a mouth full of teeth,” and these are adapted for the
capture and mastication of insects and other small and low organized
animals.
The genus Phascogale (PI. 98, fig. 3) is characterized by:
Incisors — ; canines— ; premolars— ; molars — : — 46.
In this dental formula may be discerned a step in the transition
from the Dasyures to the Opossums, not only in the increased
number of spurious molars, but also in the shape and proportions
of the incisors. In the upper jaw the two middle incisors are
longer than the rest, and separated from them by a brief interval;
they are more curved and project more forward. The three lateral
incisors diminish in size to the outermost. The middle incisors
of the lower jaw also exceed the lateral ones in size, and project
beyond them but not in the same degree, nor are they separated
from them by an interval, as in the upper jaw. The canines are
relatively smaller than in the Dasyures. The spurious molars present
a similar form, but the third in the lower jaw is smaller and simpler
than the two preceding ones. The true molars resemble those of
the Dasyures.
The general character of the dentition of these small predatory
Marsupials approximates to the insectivorous type, as will be exemplified
in the Shrew, Hedgehog, &c. among the placental Mammalia,
and corresponds with the food and habits of the species which thus
lead from the predaceous or Sarcophagous to the Entomophagous
tribes.T
he interval is further diminished by a lost Marsupial genus