OF THE MARSUPIALIA. 323 
the Opossum; and the anterior single cusp is wanting in the true molars of the lower 
jaw. 
Anterior to the grinders in the Phalanger, there are two spurious molars, of similar 
shape and proportions to those in the Opossum ; then a third spurious molar, too small 
to be of any functional importance, separated also, like the corresponding anterior false 
molar in the Opossum, by a short interval from those behind. 
The canine tooth but slightly exceeds in size the above false molar, and consequently 
here occurs the first great difference between the Phalangers and Opossums ; it is how- 
ever only a difference in degree of development ; and in the Ursine and other Phalangers, 
as well as in the Petaurists, the corresponding tooth presents more of the proportions 
and form of a true canine. 
The incisors, which we have seen to be most variable in number in the carnivorous 
section, are here three instead of five on each side, in the upper jaw; but their size, 
especially that of the first, compensates for their fewness. 
In the lower jaw, there is the same number of true molars and of functional false 
molars, which form a continuous and tolerably equable series, as in the Opossums, on 
each side ; then two very minute and rudimental teeth on each side represent the small 
spurious molar, and small canine of the upper jaw ; and anterior to these, there is one 
very small and one very large and procumbent incisor on each side. 
The constant teeth in this group are = true molars, and = incisors. The 
; 1 i : f 2 BI, 2 
canines ;—; are constant in regard to their presence, but variable in size ; they are al- 
ways minute in the lower jaw. With respect to the spurious molars, =e they are 
always in contact with the true grinders, and their crowns reach to the same grinding 
level ; sometimes a second spurious molar is similarly developed on each side of both 
jaws, as in the Phal. Cookii, and as in all the flying Phalangers, or Petaurists; but in 
other Phalangers it is absent or replaced by a very minute tooth, shaped like a canine : 
so that between the posterior spurious grinder and the incisors we may find three teeth, 
of which the posterior is the largest, as in Phal. Cookii ; or the smallest, as in Phal. 
cavifrons ; or there may be only two teeth, as in Phal. ursina and Phal. vulpina, and the 
species, whatever that may be, which Fr. Cuvier has selected as the type of the den- 
tition of this Genus. 
In the lower jaw similar varieties occur in these small and unimportant teeth; e. g. 
there may be between the procumbent incisors and the posterior false molar, either four 
teeth, as in Phal. Cookii; or three, as in Phal. cavifrons ; or two, as in Phal. ursina, 
Phal. maculata, Phal. chrysorrhoos ; or lastly, one, as in Phal. vulpina, and Phal. Fuligi- 
nosa. 
The most important modification is presented by the little Phal. gliriformis of Bell, 
which has only three true molars on each side of each jaw. 
2u2 
