The Donaldsonville chief. [volume] (Donaldsonville, La.) 1871-current, 1912-08-03
SOME THING ABOUT RATS.

Natural History Of the Little Anima
which. Science Holds to be Pri
mariIy Responsible for the Prop
agation and Spread of Buhonie
Plague.
In view Of the prevailing wide.
spread interest in rats, recognized as
the principal agents in tthe propaga-
tlon and spread Of bubonic plague,
winch has made its appearance in
Cuba and Porto Rico and threatens
to invade the Atlantic and Gulf ports
OF the United States, The Chief
gives space to the following timely
article from the pen Of DR.. David e.
Lantz, an assistant in the biological
survey of the United States depart
ment of agriculture, wherein the
natural history Of the rat is outlined
II most interesting manner:
the determination of rats has be-
come one of the serious problems of
modern times. That such noxious
animals should have flourished so
long is not creditable to our civiliza-
tion. While no kind OF rat can be
regarded harmless, the various species
differ greatly in harmfuIness. In.
comparison with the cosmopolitan
species that reach our shores from
the Old World, our native rats do
little damage. It, is important, there
fore, to be able to recognize the in
troduced forms, to understand their
naD1ts, and TO concentrate efforts for
their extirpation
Classification of Rats.
Rats and mice belong to the roden-
tia, an order which comprises more
than third of all living species Of
mammals. Also, it exceeds any other
mammalian order in the. number Of
its individuals.
Rodents are mainly herbiVorous
mammals, mostly of small size, hay-
ing a furry, sometimes a spiny, in
tegument, c1aWed digits, and usually
plantlgrade feet. The most import
ant distinguishing character of the
order is its dentition This is
marked by the absence of canine |
teeth and the presence of strongly |
developed incisors growing from
permanent pulps. The ineisors are
never more than two in the lower
Jaw and usually but two in The. up
per. They are elongated, curved, |
in shape and continue to !
Grow throughout the life of the ami
NAL. Only the front Of these teeth |
Is covered with enamel, provision
which Keeps them sharp BY g more 4
rapid wearing away Of the softer |
1entine in the body Of the tooth, as
The upper and lower pairs meet in |
snaWing. Between the incisors and /
he cheek, or molar, teeth of rodents
there is a wide, vacant space, mark
ng the entire absence Of CANNES.
The most extensive family of ro-I
tents is the Muridae, a name which
applies to rats and mice in the
widest sense of those terms. It is
difficult to characterize the family, L
since its members differ widely. How
ever, most of them are rat-like in
.orm and light and active in move
nents. None Of the family have
oremolars; and, except in a single
,enus lHydromys), the number of
nolars is three. Oldfield Thomas,
he eminent English zoologist, in
,ludes in this family no less than Z
genera, or almost half the total Of
I9 which he ascribes to the whole
order of Rodentia. He further sub
1ivides the Muridae into dozen SUBJ
antilles, of which the Murinae and
he Sigmodontinea are the most ex-
.ensiye. The name Cricetinae is
low generally used instead OF Sig
he same limitations.
The Murinae comprise only Old
World rats and mice, while the
are, in the main, Ameri-
,an forms. In the Murinae the cusps,
or tubercles, of the unWorn upper
nolars are arranged triserially, or in
hree longitudinal rows; in the Crice-
inae they are arranged biserially one.
'oW on the outer and one on the in
Ter margin. The wearing away of
hese cusps leaves characteristic
;urVed lines Of hard enamel sur
areas of dentine. When
he cusps are in pairs the worn pat
ern looks somewhat like the Greek
ettef sigma ~, whence the name
igmodont, often applied to native
American rats and mice.
The Murinae are the true rats and
nice, typified by the genus Mus,
which contains by far the largest
lumber of species. Trouessart, in
lis Catalogus Mammalian, numerates