The third group of the Australian Mammalia consists of the Rodents, which are largely represented, and, to some extent, partake of the structure of the Kangaroo; many having their hind limbs much elongated, and moving by a succession of jumps, in which they use the hind legs only. A few (4 species) are aquatic (Hydromys), expert swimmers and divers, and a great many are arboreal, and apparently the representatives of the squirrels in Australia.

All the species observed by me on the Lower Murray, are strictly nocturnal, and all bring forth 4 young ones (born blind) at a time.

1. Hydromys chrysogaster.

Golden-bellied Beaver Rat.

All the specimens of this rat procured by me are from Gun-bower Creek and Lake Boga, where this animal re very plentiful. page 4 It is strictly nocturnal, and was often observed after sundown, gambolling upon the shores of that beautiful lake. The Black Snake is a sore enemy to the young progeny of this Hydromys; for I captured a specimen, which, upon being opened, proved to have swallowed a full dozen young Beaver Rats, about the size of new-born kittens.

This Rat is not found on the Lower Darling, at least, I was assured by the natives that they had never seen it.

2. Hapalotis conditor.

Building Hapalotis.

Koel or Kohl of the natives.

Captain Sturt described this animal first, though Sir Thomas Mitchell mentioned it before him.

It is one of the many species which will soon be extinct, as I found that it had already retreated before the herds of sheep and cattle across the Murray. Only a few empty nests were occasionally met with south of that river. The few specimens collected were captured by the natives about 10 miles north of the Darling Junction; though many empty nests, or rather huts, were met with, occupied by Hapalotis apicalis, which, it appears, often takes a fancy to the roomy structures of the building Hapalotis, and ejects the original inhabitant. I kept both species together in a box, but they never agreed, and, though the building Hapalotis is much larger in size, it could never hold its own against Hapalotis apicalis. They feed on various seeds, bulbous roots, insects, and the smaller species of Hapalotis, or birds' eggs, &c., and bring forth 4 young at a time.

3. Hapalotis apicalis.

White-tipped Hapalotis.

Tillikin of the natives.

Mr. Gould figures this species, of which he mentions merely that he received it from South Australia. I observed the first specimens in the neighbourhood of Euston, and found it in great numbers upon Sir Thomas Mitchell's old track on both sides of the Murray. It also occurs on the Darling, and I have no doubt page 5 that the late lamented Explorers called Rat Point (in the neighbourhood of fort Bourke) after this Hapalotis.

They are gregarious in their habits. I have dislodged as many as 15 specimens from a single tree, and kept large numbers in captivity. They became quite tame; and many which had escaped would return to join my frugal supper at night, and help themselves, to damper especially. This is a very graceful animal, strictly nocturnal in its habits, and its flesh white, tender, and well-tasted.

4. Hapalotis Mitchellii.

Mitchell's Hapalotis.

Kahlpere of the natives—

is another animal which the late Sir Thomas Mitchell first discovered. I have no doubt that it is widely distributed over the Australian continent, but I was not able to procure specimens at Gunbower Creek, or at the Junction of the Loddon. The first pair obtained were brought to me by natives in the neighbourhood of the Murrumbidgee. This animal is very plentiful on the Darling: and as many as 50 specimens were often procured by the native women in an afternoon. It burrows into the ground, and is dug out by them. Hapalotis Mitchellii is strictly nocturnal in its habits, and the female produces 4 young at a time. Though they are easily kept in captivity, they often kill each other, if not well supplied with food; they also have a disagreeable habit (to the naturalist, at least) of gnawing each others toils off.

5. Mus subrufus?

Dusky mouse.

Pethack of the natives.

Apparently an undescribed species (for which I would propose the name of Mus subrufus) is found in large numbers between Gol Gol Creek and the Darling; it is nocturnal and gregarious, and, like Hapalotis Mitchellii, burrows into the ground; 4 young are produced at a time by the female.

All the Rodents are eaten by the natives, but only in case of no other food being at hand, as a large number of these little creatures are wanted to satisfy the hunger of a black-fellow.

This closes the list of the Placental Mammalia, which I had page 6 an opportunity of observing. But there are, no doubt, still many species of Rodents new to science; in fact, several skins of Hapalotis were received through native tribes living some 100 miles further north, but all were in such bad preservation, that it was found impossible to give a correct description of them.