GERBILLUS AFER.
Teeth, &c.—Incisors of upper jaw rather slender, protruding about a
line and a half beyond the alveoli, their points sharp and formed for cutting,
the anterior surface of each divided longitudinally by means of a deep and
narrow furrow; the incisors of the lower jaw about twice the length of those of
the upper, moderately strong, and without a furrow. The first molar of the
upper jaw is composed of three divisions, and the others of two, and each
division, as seen in the crown of the teeth, resembles a flattened tube, with
its edges in some almost in contact about midway between the outer and
inner extremities, in others the distance between the sides is throughout
nearly equal or even greater about their middle than at the extremities.
The hinder tooth is much smaller than the second, which again is
considerably inferior in size to the first. Tfye first and second molars of
the lower jaw consist of the same number of divisions as those of the upper;
the third is entire, and in form is like one of the other divisions. The ossa
nasi are lines in length; the distance between the upper incisors and the
base of the first molar six lines, and the length of a row of molars three lines.
Specimens of this animal are to be obtained in abundance at the Cape of Good Hope, and
there is no difficulty in procuring them even in the immediate vicinity of Cape Town. It is
known among the Colonists by the name of Nacht-muis, which appellation it has received
from the circumstance that it rarely leaves its burrow excepting in the night, and that all its
operations are carried on under the cover of darkness. It is commonly found in open plots of
ground, which are clothed with a short grass, and situated in the vicinity o f brushwood, and in
such situations a number of individuals generally congregate and form their burrows, extending
them in different directions so as not to interfere with each other. The courses of the
burrows are at first oblique, but after reaching into the soil to about a foot in depth, they commonly
run horizontally, and frequently are from three to four yards in length, and it sometimes
happens that one intersects or communicates with another in its course. When young are
about to be brought forth, a nest of soft grass is formed at the distal extremity o f the subterranean
passage, and in it they are placed until they are able to run about and provide for themselves.
The nackt-muis rarely continues for any great length of time in one situation; hence
it may be considered as by nature a truly migratory animal. When it leaves one locality to
take up its abode in another, it performs the journey during the night, and manages its time so as
to be able to form a portion of its new habitation at least,.before day-light appears. Specimens
are most readily procured by digging in the course of the burrows, but care must be taken to
ascertain that they are actually inhabited at the time they are discovered; else much labour
may be expended without an individual being captured. The ground immediately adjoining
the holes must be closely examined; and if, on such examination, no recent footmarks can be
discovered, it may be inferred that they are the abandoned burrows of some family which
has taken up its residence elsewhere»