262 
into a thumb, but without a claw. The hinder 
d is associated in almost all the species 
with a scaly prehensile tail. 
In some of the smaller Opossums the sub- 
abdominal tegumentary folds are rudimental, 
or merely serve to conceal the nipples, and are 
not developed into a pouch: the young in 
these species adhere to the mother by entwining 
their little prehensile tails around her's; and 
they cling to the fur of the back, hence the 
term dorsigera applied to one of these Opos- 
sums.* 
Tribe 1II. CARPOPHAGA. 
Stomach simple ; caecum very long. 
In this family the teeth, especially those at 
the anterior part of the mouth, present consider- 
able deviations from the previously described 
formule ; the chief of which is a predomi- 
nating size of the two anterior incisors, both 
in the upper and lower jaws. Hitherto we 
have seen that the dentition in every marsupial 
genus has participated more or less in a carni- 
vorous character ; henceforth it will manifest a 
tendency to the Rodent type. 
Genus PHALANGISTA. 
The Phalangers, so called from the phalanges 
of the second and third digits of the hinder ex- 
tremity being inclosed in a common sheath of 
integument, have the innermost digit modi- 
fied to answer the purposes of a thumb; and 
this hinder hand being associated in many of 
the species with a prehensile tail, they evidently, 
of all Frugivora, come nearest to the arboreal 
Species of the preceding section. In a system 
flamed on locomotive characters they would 
rank in the same section with the Opossums. 
We shall see, however, that they differ from 
those Entomophagous Marsupials in the con- 
dition of the intestinal tube. Let us examine 
to what extent the dental characters deviate 
from those of the Opossums. 
Fig. 86. 
In the skull of a Phalangista Cookii, of 
which the dental formula is accurately given 
in fig. 86, there are both in the upper and 
lower jaws four true molars on each side, each 
* Few facts would be more interesting in the 
present branch of zoology than the condition of 
the new-born young, and their degree and mode of 
uterine development in these Opossums. Since 
the marsupial bones serve, not as is usually de- 
scribed to support a pouch, but to aid in the func- 
tion of the mammary glands and testes, they of 
course are present in the skeleton of these small 
pouchless Opossums as in the more typical Mar- 
supials. 
MARSUPIALIA. 
beset with four three-sided pyramidal sharp 
pointed cusps; thus these essential and mos 
constant teeth correspond in number with tho 
of the Opossum: but in the opps jaw t 
differ in the absence of the internal cusp, whi 
gives a triangular figure to the grinding surface 
of the molars in the Opossum; and the ; 
terior single cusp is wanting in the true mola 
of the lower jaw. Anterior to the upp 
grinders in this Phalanger there are two pi 
molars of similar shape and proportions — 
those in the Opossum; then a third premok 
too small to be of much functional importan 
separated also, like the corresponding ante 
premolar in the Opossum, by a short inter 
from those behind. 4 
The canine tooth but slightly exceeds in siz 
the above false molar, and consequently he 
occurs the first great difference between 
Phalangers and Opossums; it is, howe’ 
but a difference in degree of development ; ai 
in the Ursine and other Phalangers, as well 
in the Petaurists, the corresponding tooth pi 
sents more of the proportions and form o 
true canine. é 
The incisors, which we have seen to be n 
variable in number in the Carnivorous 
are here three instead of five on each 
the upper jaw, but their size, especially th at 
the first, compensates for their fewness. 
In the lower jaw there is the same n 
of molars and functional premolars as in | 
Opossums ; the two very minute ard funeti 
less molars, which form part of the same 
tinuous series, represent the small premolar 
canine of the upper jaw; and anterior ‘o th 
there is one very small and one bee’ rge 
procumbent incisor on each side. Now if | 
comparison be just and natural, the differ 
in the number of teeth between the Phalar 
and the Opossum will resolve itself into 
former being minus certain incisors in the 
per and lower jaws: in the latter, the g 
development of the middle incisors as 
produce an atrophy of all the rest. 
The interspace between the functionals 
veloped incisors and molars in both jaws als 
contains in the Phalangers teeth of small 
and little functional importance, and vai 
not only in their proportions but their nu 
The constant teeth in the Phalangers are 
4—4 3—3 . 
—- —_—— JNCISG 
a 
true molars, and the 
— ve 
Fig. 87. 
