Family SiURIDÆ
RATS, MICE, AND VOLES
T he MttricUe differ from the. rodents
cheek teeth: there are the usual three
premolars are absent. The cheek tec
they may be rooted or rootless. In
and -in others the grinding surface ;
partments, which may be—-as in the
—as in the Field Vole—separated bv
postorbital processes, and the infra»«
slender. The1 first toe on the
small claw. The tail is general h
fine hair. The ears are round and
found in our island-—the M utina ■
sviousiy referred to in the number of the
Its of molars present in each jaw, but the
in this family are variable in structure:
se cases they are surmounted by tubercles,
:vHcned and divided into prisms or com-
*k Vole—connected by hollow channels or
ow. walls of enamel. The skull is without
U opening is large; the malar short and
is rudimentary, in some species only a
and scaly, but sometimes is clothed with
, the collar-bone complete,
j? representatives of two sub-families are
ats and Mice, and the M icrottna, or Voles.
-family M u r in æ
Genus Mus
Mice and R ats
There are more sp« • ■ in Linnaeus’ genus M us than in any other mammalian
genus, and even in the recognised species there is great tendency to insular and
even local variation. Rats and Mice are found throughout the globe, with the
exception of Madagascar, for in Australia we have the allied genus Hydromys.
In their general form the term ‘ rat-like’ is sufficiently descriptive—small-sized
animals with pointed muzzles, long scaly tails, large ears, dark prominent eyes,
soft dense fur, and abundant vibrissæ. The incisor teeth—a single pair in each
jaw—are strong, smooth (not grooved), and narrow ; on the external surface they