394 
HORN EXPEDITION—MURIDS. 
witness the number of new species discovered by Professor Spencer in tlie 
comparatively well-worked order of the Marsupialia. 
“ Most of the specimens were collected in districts having similar features— 
hard sandy ground covered with sparse scrub of Mallee gum, Cassias, Eremophilas, 
and Mulga. The mice construct burrows, usually close to the base of a shrub. 
The burrow is simply a small hole in the ground just large enough to admit the 
mouse; it goes slanting steeply downwards for two, three, or even four feet. In 
each instance there appeared to be more than one pair inhabiting the same 
burrow.” My informant says that he “once counted nine specimens of the rather 
larger species, with a whitish belly (Afi/s gouldi), of which five wei’e adult, and 
four young of fair size, together with other smaller young ones being suckled by 
two females. A rough nest is made of bits of grass lying on the floor of fhe 
burrow where it was slightly hollowed out, on which the females with young were 
lying. On smelling this grass in a burrow the blackfellow will at once say 
whether the animal is ‘ at home ’ or not. The smaller and darker-coloured mouse 
{AIus niusathis) is very common on the hard sandy and stony plains about Charlotte 
Waters, but is not found in the looser sandy districts near the creek beds.” 
Professor Spencer, who has kindly furnished the foregoing valuable and 
interesting information, tells me that he did not himself obtain the larger species 
{^Co 7 iiluruspedunculatus)^ and has no particulars of it beyond the locality and the 
peculiarities below mentioned. 
One of the interesting features of the collection is the finding of Mastacomys 
living in Australia, and although this is what one would naturally expect, seeing 
that it at present exists in Tasmania, the genus was previously known only as 
fossil on the continent. 
The examples of Mus inusculus received furnishes another instance of how 
the species will accompany man wherever he goes, turning up and successfully 
colonising in the most unexpected places. Setting aside this species, and also 
Afus greyi, of which only males were collected, all the sjiecimens sent are 
characterised by the possession of four inguinal mamnue only, there being none in 
the pectoral region. Pectoral mamime, when present, are apt to be overlooked ; 
but several females of each species sent were suckling, which not only settles this 
point, but also proves them to be adult. The specimens of Mastacofnys below- 
mentioned were too young for the numlier of mammiB to be definitely ascertained, 
but Mr. Thomas lias shown that four only are present in the type. 
