398 
HORN EXPEDITION—MURID.E. 
opening one to ascertain the fact, however, the vertebne were found to be quite 
normal, and the increased diameter was caused wholly by an enormous thickening 
of the skin, for which no reason could be assigned. It is evident that the thinner 
pedicle w'uuld allow the appendage a greater degree of motion than would be other¬ 
wise possible. Apart from its peculiar form the tail appears to be very fragile, 
and out of seven specimens was perfect in two only. In the others it had been 
broken off, and in one instance a second partial fracture had occcurred, but the 
portion broken, not having been detached, had rejoined with the dark dorsal 
surface to one side. This fragility was remai'ked by Mr. Field, of Alice Springs, 
who caught the animals, and said that “ the tail very easily broke off whilst they 
were catching them; it seemed to be brittle.” It is not easy to understand the 
advantage of this peculiarity, unless indeed it is analagous to what occurs in tlie 
lizards, many of which detach their tails to escape capture; but it is not conceiv¬ 
able that a similar power of reproduction can exist. It has been previously hinted 
that this species has affinities both with Miis and Coni/uriis, with the former by 
the presence of a coronoid process in the lower jaw, and with the latter by having 
among other features a w'ell-clothed tail. To propose a new genus for Coniliirus 
pedunailatus^ a species whose tail renders it peculiar, would only add to the 
difficulty of defining the genera, and the jerboa-like character of the species 
sufficiently proclaims its affinities to the more typical examples of Conilurus. 
Mus musculus, Linn. 
A number of specimens from Charlotte Waters were in all particulars indis¬ 
tinguishable from the common house mouse. Although common enough in most 
parts of the continent, it was recognised with some surprise from Central 
Australia. On mentioning its occurrence to Professor Spencer he wrote—-“All 
along the central telegraph line there is a constant carriage of goods to the various 
outlying stations, and an odd pair may by this means have been conveyed to the 
central districts. Once established, the beast would presumably be able to spread 
widely.” He adds the interesting, if not altogether welcome- fact, that even the 
I’abbit has now made its appearance at Charlotte Waters. 
Mus gould i .0 Fig. 2, a—/. 
Waterhouse, Voy, “Beagle,” I., p. 67, pi. xxxiv., fig. 18 (molars); Gould, 
Mamm. Austr., III., pi. xix. ; Ogilby, Cat. Austr. Mamm., p. 107. 
Several specimens are provisionally referred to this species, but as they are 
much smaller than those measured by Waterhouse they may eventually prove to 
be distinct. In most other respects the original description applies to these 
examples. The following points are, however, not mentioned :—The ears when 
