Mus Musculus, _Auctorum_.
Of this species, there are six specimens in Mr. Darwin’s collection; two
were found “living in the short grass, near the summit of the Island of
Ascension, where the climate is temperate.”—D. Two others were procured
“on a small, stony, and arid island, near Porto Praya, the capital of
St. Jago, in the Cape de Verde Islands,—climate very hot and dry.
Excepting during the rainy season, which is of short duration, these
little animals can never taste fresh water, nor does the island afford
any succulent plant.”—D. A specimen was also procured “on a grassy
cliff, on East Falkland Island, at the distance of a mile from any
habitation. It is singular that so delicate an animal should be able to
subsist under the cold, and extremely humid climate, of the Falkland
Islands, and on its unproductive soil.”—D. These specimens are all of
them rather less than full grown individuals of the same species
procured in England; in other respects, they do not differ.
The sixth specimen, which is from Maldonado, is considerably less than
British specimens of the common mouse, and is of a richer and brighter
colour, the head is smaller, the muzzle shorter in proportion, whilst
the tarsi are even longer than in a large specimen of _M. Musculus_.
These points of dissimilarity induced me to believe it was a distinct
species, and to apply to it the specific name of _brevirostris_.[17]
Upon re-examination, with the advantage of more experience, and
consequently a better knowledge of the characters of these animals, I
have changed my opinion. The teeth indicate that it is not an adult
specimen, and agree perfectly with those of _M. Musculus_, both in form
and size. “Common in the houses of the town of Maldonado, and its habits
are similar to those of _Mus Musculus_.”—D.
6. MUS LONGICAUDATUS.
PLATE XI.
Mus longicaudatus, _Bennett_, Proceedings of the Committee of Science
and Correspondence of the Zoological Society of London for January,
1832, p. 2.
_M. pallidè flavescenti-fuscus; corpore subtùs albo, levitèr flavo
lavato; pedibus albis; tarsis permagnis; caudâ perlongâ; auribus
parvulis._
DESCRIPTION.—Fur long and soft; general colour pale yellow-brown, the
hairs of the ordinary fur being fulvous near the apex, and the
longer hairs brown. On the sides of the body, cheeks, and external
side of limbs, the fulvous hue prevails. The inner side of the
limbs and the under parts of the body are white, but have an
indistinct yellowish hue. All the hairs of the body are of a deep
gray colour at the base. The ears are small, well clothed with
hairs; those on the inner side are chiefly yellow; externally, on
the fore part they are brown, and posteriorly whitish. The feet
are of a flesh-colour, and furnished above with white hairs; the
tarsi are but sparingly provided with minute hairs on the upper
side, and are naked beneath: they are of unusually large size. The
fore feet are of moderate[18] size, and furnished with a very
large carpal tubercle. The tail is very nearly double the length
of the body, if the latter be measured in a straight line; it is
of a brownish flesh-colour above, paler beneath, and sparingly
furnished with minute bristly hairs; those on the upper surface
being brown, and on the under side white. The hairs of the
moustaches are long, of a black colour, and grayish at the apex.
In. Lines.
Length from nose to root of tail 3 9
of tail 5 3
from nose to ear 0 10½
of tarsus (claws included) 1 1
of ear 0 4
Habitat, Chile.
The most conspicuous characters of the present species consist in the
immense length of the tail, and the great size of the hinder feet.[19]
It is about equal in size to _Mus Musculus_; its form, however, is
somewhat stouter; in colour it is much paler and brighter. The head is
larger in proportion; the ears are smaller, and more densely clothed
with hair; the fore feet are rather larger, and the fleshy tubercle on
the under side of the wrist is also larger. The thumb nail is flattened,
and rounded at the tip, as in _Mus Musculus_, but is longer, and more
distinct than in that animal.
The skull of _M. longicaudatus_, (Plate 34, Fig. 1,) is considerably
larger than that of the common mouse, but in form scarcely differs from
it; its upper surface is rather more convex, and the interparietal bone
proportionately less. The length of the skull is 1 inch; breadth, 6½
lines; distance between the forepart of the incisor, and the first molar
of the upper jaw, 3½ lines. The dentition is figured in Plate 34, Figs.
1. _b_ and 1. _c_.
The above account is drawn up from the same specimen as that from which
Mr. Bennett took his description, and which was brought from Chile by
Mr. Cuming, who states that the animal in question lives in trees, and
constructs its nest with grass.
In Mr. Darwin’s collection, I find an animal which agrees in all the
more important characters with the one above described, but differs in
being of a deeper colour, (approaching more nearly, in this respect, to
the common mouse,) and in having the tail a trifle shorter. The skull is
about ¾ of a line shorter, but its proportions agree precisely: the
proportions of the feet, and the general form of the animal, also agree.
This specimen is likewise from Chile, (Lat 37° 40′,) and, according to
Mr. Darwin, “overran the wooded country south of Concepcion, in swarms
of infinite numbers. Captain FitzRoy, on his return from visiting the
wreck of H. M. S. Challenger, had the kindness to bring me this
specimen. So destructive was this little animal, that it even gnawed
through the paper of the cartridges belonging to the people who were
wrecked.”—D.
MUS ELEGANS.
PLATE XII.
Mus elegans, _Waterh._, Proceedings of the Zoological Society of
London for February 1837, p. 19.
Eligmodontia typus, _F. Cuvier_, Annales des Sciences Naturelles for
March 1837. Tom. 7. p. 169. Pl. 5.
_M. suprà flavus, vellere pilis fuscescentibus adsperso, his ad
latera, et prope oculos rarioribus; pilis pone aurem utramque,
labiis, corpore subtùs, pedibusque niveis; auribus magnis; caudâ
capite corporeque paulo longiore; tarsis longis subtùs pilis
obsitis._
DESCRIPTION.—Fur very long and soft; general colour of the upper parts
of the body pale brownish yellow; the lower portion of the cheeks,
and the under parts of the body pure white: the hairs of the
ordinary fur of the back are gray at the base, pale ochre near the
apex, and brown at the apex; the longer hairs are brownish. On the
sides of the body where the longer hairs are less numerous, the
pale ochre colour prevails; the hairs on this part as on the back
are deep gray at the base, but at a short distance from the apex
they are white; nearer the tip shaded into yellow, and at the tip
brownish: the limbs externally are of a pale yellow colour. The
hairs of the throat and chest are pure white to the root, those on
the belly are obscurely tinted with gray at the root. The feet are
of a pale flesh-colour, and furnished with white hairs; the fore
feet are of moderate size; the thumb nail is small and rounded,
and the carpal tubercle is covered with hairs; the tarsi are long,
and the white hairs extend over the whole of the under parts; the
under side of the toes, however, are but sparingly furnished.
There appears to be but one large tubercle on the under side of
the tarsus, and this, which is situated near the base of the toes,
is thickly covered with silvery-white hairs. The tail is long,
pale brown above, and pale flesh-colour beneath; above, it is
furnished with minute brown hairs, and on the under side with
white hairs. The ears are rather large, of a pale flesh-colour,
tolerably well clothed with hairs, which are of a pale yellow
colour on the inner side, and white on the outer side—excepting on
the fore part, where they are brown. A small tuft of white hairs
springs from the base of the ear posteriorly. The hairs of the
moustaches are moderate; black at the base, and grayish at the
apex.
In. Lines.
Length from nose to root of tail 3 7
of tail 3 9
from nose to ear 1 0
of tarsus 0 10
of ear 0 6