D Entomophaga. In this section the jaws are always furnished with canine teeth, but these are not of very large size, and the animals composing the section are therefore not highly predaceous, but "prey, for the most part, on the smaller and weaker classes of invertebrate animals." In this section are the Bandicoots ( Peramelidae), the American Opossums (Didel-phidae), and the Banded Ant-eater (Myrmecobius).

* The name "Bandicoot" properly belongs to the Great Rat (Mus giganteus) of India.

The Bandicoots * (Peramelidae) are small Australian animals, which appear to fill the place of the Hedgehogs, Shrew-mice, and other small Insectivora of the Old World. The molars are cuspidate, and canines are present (fig. 364, B). The dental formula is:

i

5-5

; c

1 - 1

; pm

3-3

; m

4-4

=

48.

3-3

1 - 1

3-3

4-4

The hind-limbs in the Bandicoots are considerable longer than the fore-limbs, and their progression is therefore by a series of bounds. The fore-limbs have really five toes each, but only the central three of these are well developed, the outermost and innermost digits being rudimentary. The three functional toes are armed with long strong claws, with which the Bandicoots burrow with great ease. The marsupial pouch - and this is a singular point - opens backwards instead of forwards. In the nearly-allied genus Chaeropus, also from Australia, the fore-foot has only two functional digits (the 2d and 3d), the 1st and 5th digits being wanting, and the 4th being rudimentary; while the 4th digit of the hind-foot is the only functional toe.

The second family of this section - namely, the true Opossums or Didelphidae - is remarkable in being the only group of the whole order which occurs out of the Australian province. The Didelphidae, namely, are exclusively found in North and South America, where they are known as "Opossums." A considerable number of species is known, but they are mostly of small size, the largest measuring not more than from two to three feet, inclusive of the tail. The Virginian Opossum (Didelphys Virginiana) is the only member of the family which is found in North America, and it was the earliest Marsupial known to science; its place in South America being taken by the widely-distributed Didelphys D'Azarae. Most of the Opossums are carnivorous, feeding upon small quadrupeds and birds, but they also eat insects, and sometimes even fruit. One species (Didelphys cancrivora) lives chiefly upon Crabs; and the Yapock (Cheironectes) has webbed feet, and leads a semi-aquatic life. All the Didelphidae have the hallux nail-less and opposable to the other toes, so as to convert the hind-feet into prehensile hands, and all have a more or less perfectly prehensile tail, these being adaptations to an arboreal life. The marsupial pouch is sometimes not present in a complete form, but is merely represented by cutaneous folds of the abdomen concealing the nipples. In the Didelphys dorsigera, in which this peculiarity obtains, the young soon leave the nipples, and are then carried about on the back of the mother, to whom they cling by twining their prehensile tails round hers. The dentition of the Opossums (fig. 366) is remarkable for the great number of the incisor teeth, the dental formula being:

i

5-5

; c

1 - 1

; pm

3-3

; m

4-4

=

50.

4-4

1 - 1

3-3

4-4

The canines are well developed, and the crowns of the molars are cuspidate.

Fig. 366.   Dentition of Opossum (Didelphys).

Fig. 366. - Dentition of Opossum (Didelphys).

The Banded Ant-eater (Myrmecobius fasciatus) is a small but extremely elegant little animal, which inhabits Western and Southern Australia, and lives upon insects (fig. 367). The tail is bushy, and differs from that of the Didelphidae in not being prehensile. The fore-feet have five toes armed with claws; the hind-feet have only four toes. The Myrmecobius is remarkable for the extraordinary number of molar teeth, in which it exceeds any existing Marsupial, and is only surpassed by some of the Armadillos. The dental formula is:

i

4-4

; c

1 - 1

; pm

3-3

; m

6-6

=

54.

3 - 3

1 - 1

3-3

6-6