FAUNA OF THE MONTE BELLO ISLANDS. 631 
it is one of the most defenceless animals that can well be 
imagined. It is easily dislodged from its hiding-place amongst 
the Spinifex, from which it often rises in an awkward fashion, 
tripping up and rolling over before getting away. Though it is 
able to hop swiftly for a short distance, it rapidly becomes ex- 
hausted, and is not difficult to obtain by simply running after 
it and catching it by the tail. 
The breeding:season appears to be during the summer and is 
possibly dependent upon the rains, for we saw no half-grown 
specimens, and as the rains of the previous summer had failed, 
they may not have bred at all. It is possible, however, that the 
eats had accounted for all the young ones. The pouches of all 
the females were empty, but in the middle of August males and 
females were often seen in pairs. 
The species under consideration offers a very striking example 
of “degeneration” resulting from isolation and consequent 
absence of enemies. Owing to the lack of surface-water upon 
these islands, it has never had to face the dingo and the 
aborigines, who would make short work of an animal so easily 
caught. It is remarkable that it has been able to brave the 
climatic conditions for so long, and has not succumbed to a par- 
ticularly severe drought or cyclone. ‘The identity of this species 
with that of Barrow Island indicates a comparatively recent 
land-connection, but from all the other smaller islands, which 
presumably formed part of the same land-mass, the species has 
disappeared. 
9. IsooDON BARROWENSIS Thom. 
Only shrivelled skins and bones of this species were discovered, 
but skulls correspond in all essentials with specimens from Bar- 
row Island, with which it is in all probability identical. The 
cats have evidently been responsible for its extermination. Its 
distribution corresponds exactly with that of the species last 
described, and here again it is quite distinct from the corres- 
ponding mainland form. 
3. Epresicus PUMILUS Gray. 
This little bat occurs on the North-West Australian mainland, 
and is not uncommon over the whole Monte Bello Group, 
appearing upon the wing about sunset. It was generally 
observed near rocks and cliffs, where it probably spends the 
day. 
Introduced species.—It is curious to find Mus rattus particularly 
common on the small outlying islands of the group which have 
never been inhabited, frequenting the beaches and sand-hills 
near the coast. It occurs on practically every island, and its 
presence is attributed to a pearling-schooner which was wrecked 
some twenty years ago. All the specimens we obtained were 
