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MARSUPIALIA. 
The canines (c. fig. 86 and 87,) are constant 
in regard to their presence, but variable in size ; 
they are always very small in the lower jaw. 
With respect to the functional premolars 
1—1 
1—1 
molars, and their crowns reach to the same 
inding level; sometimes a second premolar 
is similarly developed in the upper jaw, 
as in the Phal. Cookii, and as in the great 
flying Phalangers, (Petaurus Taguanoides, 
fe. 88) but it is commonly absent, or re- 
placed by a very minute tooth, shaped like a 
canine ; so that in the upper jaw, between the 
posterior or functional premolar and the in- 
cisors, 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 
these are always in contact with the 
Phat. vulpina, and the species, whatever that 
may be, which M. Fr. Cuvier has selected as 
the type of the dentition of the 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 premolar, either three teeth as in 
Phal. Cookii and Phal. cavifrons, or two, as 
in Phal. ursina, Phal. maculata, Phal. chry- 
sorrhoos ; or finally one, as in Phal. vulpina 
and Phal. fuliginosa. 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. As these 
modifications of the teeth are unaccompanied 
by any change of general structure or of habit, 
whilst those teeth which most influence the diet 
are constant, it is obvious that these differences 
of dentition are unimportant, and afford no 
just grounds for subgeneric distinctions. 
The Phalangers, being provided with hinder 
hands and prehensile tails, are strictly arboreal 
animals, and have a close external resemblance 
to the Opossums, by which name they are 
generally known in Australia and the Islands 
of the Indian Archipelago, where alone they 
have hitherto been found. They differ from 
the Opossums chiefly in their dentition; and in 
esce with this difference their diet is 
more decidedly of a vegetable kind.* The 
Australian Phalangers feed chiefly on the ten- 
der buds and the leaves of Eucalypti: but 
according to Temminck,+ the Indian Phalan- 
ers are omnivorous, and combine insects with 
its and leaves. Mr. Ogilbyt states that 
both “ the Phalangers and Petaurists display 
so decided a tt Sess for live birds, as to 
make it probable that these constitute a main 
rtion of their food in a state of nature.” I 
nd, however, that the intestinal canal, and 
especially the caecum, offers so great an addi- 
tional development in length, as, with the cor- 
responding predominance of the incisors, and 
atrophy of the canines, to indicate clearly a 
* In the stomach and intestines of specimens 
sent to me in spirits from Australia, I have never 
fonnd any other alimentary substances but those of 
a vegetable nature. 
+ Monographies de Mammalogie, p. 3. 
$ Mag. Hist. Nat. 1837, p. 458. 
263 
natural and constant tendency in the Phalangers 
to a vegetable diet. Guided theyefore by the 
totality of their organization, I am led to place 
them in a distinct section from that which con- 
tains the Opossums, but, in that section, they 
come the nearest to the true Opossums. The 
Phalangers of the Indian Isles have short ears 
and the greater part of the tail naked. To this 
group have been applied the names Ceonyz, 
Cuscus, and Balantia ; the Australasian Pha- 
langers have moderately long ears, and the 
greater part, or else the whole of the tail is 
covered with hair. All the species possess 
considerable freedom of lateral movement in 
the anterior digits, and in some small species, 
as Phal. gliriformis, Bell, they appear to be 
naturally divided into two groups, the two 
outer being opposed to the three inner fingers. 
To the hairy-tailed Phalangers exhibiting this 
character, Mr, Ogilby gives the subgeneric 
name Pseudocheirus, restricting the term Phalan- 
gista to the remaining species. With reference 
to the subgenera Cuscus, Bualantia, Pseudo- 
cheirus, &c. I heartily concur in the opinion 
of the experienced and judicious Temminck,* 
that these numerous sections are perfectly use- 
less, and a burthensome charge to the memory. 
Genus PETAURUS. 
There are many species of Marsupialia limi- 
ted to Australia and closely resembling, or 
identical with, the true Phalangers in their den- 
tal characters and the structure of the feet. I 
allude to the Petaurists or Flying Opossums : 
these, however, present an external character 
so easily recognizable, and influencing so ma- 
terially the locomotive faculties, as to claim 
for it more consideration than the modifica- 
tions of the digits or spurious molars which 
we have just been considering in the Pha- 
langers. A fold of the skin is extended on 
each side of the body between the fore and 
hind legs, which, when outstretched, forms a 
lateral wing or parachute ; but which, when the 
legs are in the position for ordinary support or 
progression, is drawn close to the side of the 
animal by the elasticity of the subcutaneous 
cellular membrane, and there forms a mere te- 
gumentary ridge. These delicate and beautiful 
Marsupials have been separated generically from 
the Phalangers under the name of Petaurus: 
they further differ from the Phalangers in want- 
ing the prehensile character of the tail, which, 
in some species of Petaurus, has a general 
clothing of long and soft hairs, whilst in others 
the hairs are arranged in two lateral series. 
Now in the Petaurists there is as little con- 
stancy in the exact formula of the dentition as 
among the Phalangers. The largest species of 
Petaurus (Pet. Tuguanoides) for example, is 
almost identical in this respect with the Pha- 
langista Cookii, which M. Fr. Cuvier has 
therefore classed with the Petauri. Those 
teeth of Pet. Taguanoides which are sufficiently 
developed, and so equal in length, as to exer- 
cise the function of grinders, or in other words, 
the functional series of molars, includes six 
teeth on each side of the upper jaw, and five 
* Loc. cit. p. 10. 
