HARVARD UNIVERSITY.

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OF THE
MUSEUM OF COMPARATIVE ZOOLOGY.

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AIDS TO THE IDENTIFICATION

Rats connected with Plague in India, with
Suggestions as to the Collection
| of Specimens.

BY

W. C. HOSSACK, M.D.,

Plague Department, Calcutta.

Published by the Trustees of the Indian Museum.

2nd EDITION.

PRICE, EIGHT ANNAS.

PRINTED AT THE PIONEER PRESS,
ALLAHABAD.

—=

‘4 BOOP.

PRESENT BD

BY

Ghe Crustees

OF

THE INDIAN MUSEUM.

AIDS TO THE IDENTIFICATION

OF

Rats connected with Plague in India, with
Suggestions as to the Collection
of Specimens.

BY

W. C. HOSSACK, M.D.,

Plague Department, Calcutta.

Published by the Trustees of the Indian Museum.

2nd EDITION.

PRICE, EIGHT ANNAS.

PRINTED AT THE PIONEER PRESS,
ALLAHABAD.

=

1907.

PREFACE TO SECOND EDITION.

The issue of a second edition has given me an opportunity to
make a few slight additions to the original note. The most
important of those is the paragraph calling renewed attention to
the necessity for using a comparatively large amount of spirit.
Unfortunately many of the consignments of rats which have
been sent to the Museum up to date have arrived in bad con-
dition with the hair coming off, as the result of neglecting to
carry out the precautions called for.

Wm. C. HOSSACK, M.D.,
Plague Department.

CALCUTTA :
November 2nd, 1907,

INTRODUCTORY NOTE.

The literature on Oriental rats is scattered in many scientific
Periodicals and other publications more or less inaccessible to the
ordinary man, be he naturalist or doctor, who desires information
regarding these important animals. Partly for this reason, and
partly because the lust for the creation of new species burns so
strong in the breasts of myologists, it is no longer possible for even
a trained observer to feel confidence in this own identification of
examples of many of the more obscure forms, without a prolonged
preliminary study of the question. Although some obscurity still
exists—and can only be dispelled by an examination of a large
number of specimens from a large number of places—as regards
even the common species found closely associated with man in
India, the identification of these is even now in most cases more
difficult than it need be. With a view, therefore, both of faci-
litating the diagnosis of the house-rats of India and of obtaining
material for a more comprehensive study, it was suggested to the
Government of India through the Board of Scientific Advice, that
some co-ordination should be brought about among those working
on rats, in connection with plague or otherwise, in different parts of
India. As Government agreed that this was advisable and that
the first steps should be taken by the Natural History Section of
the Indian Museum, the present pamphlet was prepared. Its
issue has been rendered possible by the energy of Dr. W. C.
Hossack, who has recently devoted considerable time and
patience to the study of Indian house-rats. Those who desire
fuller information on the subject are referred to the more detailed
account by the same author of the species occurring in Calcutta ;
this will be issued shortly by the Trustees in the first volume of
the “Memoirs of the Indian Museum.”

It is greatly to be hoped that those who are interested either
in zoology or sanitary and medical science and have the oppor-
tunity, will assist the Indian Museum in the survey of the
Indian rats which it proposes to commence, both by forwarding

ll
specimens to the Museum and by recording the facts which are
noted by Dr. Hossack as being of importance in connection with
the identification of specimens. In any publication of results the

collectors’ names will be recorded and credit will be given them
for any notes of which use is made.

All communications or parcels should be addressed to—
THE SUPERINTENDENT,
Indian Museum (Nat. Hist. Section),
Calentta,

and will be duly acknowledged. It is hoped that arrangements
may be made later for the distribution of simple measuring
apparatus to those who undertake to assist the Museum.

N. ANNANDALE,
Officiuting Superintendent.
INDIAN MUSEUM:
Caleutta, Murch 21st 1907.

A SHORT NOTE

ON THE

Indian Rats probably concerned in the propaga=
tion of Plague, with instructions as to
the preservation and measure=
ment of specimens.

The fact that rats play an all-important part in the propaga-
tion and maintenance of endemic plague has resulted in the issue
of instructions from the Government of India for the preparation
of a pamphlet for the guidance of Medical Officers and others
engaged on plague work. The goal at which the pamphlet aims
is that our knowledge of the rats chiefly concerned with plague,
their habits and distribution, at present sadly deficient, shall be
so extended and amplified that we may be able to collect a
sufficiently comprehensive and accurate mass of facts to justify
final and definite conclusions. It is proposed to attempt to
achieve this aim by presenting a short and clear account which
will make it comparatively easy for any one at all interested in
the subject te identify the common rats occurring in his district,
and in the second place by the preparation of a series of instruc-
tions as to the preservation and labelling of specimens.

As the result it is hoped that the authorities of the Indian
Museum will soon find themselves in the possession of such an
amount of well preserved and accurately described material as
to enable them to attack the problems at present awaiting
solution, problems that only a widespread and systematic collec-
tion of specimens can settle.

The great dithculty in dealing with rats from the zoological
point of view is that in external appearance there is extremely
little difference, so that, to one who is not an expert, specimens
belonging to entirely different genera may present an apparently
identical appearance. As a matter of fact, if sufficient attention
is paid to minute details of measurement, such as the relative
proportion borne by the hind feet to the total length of the head
and body, there is little difficulty in separating genera, but with
regard to species, particularly of the genus Mus, the points of
difference relied upon are so minute and ill-defined that the sub-
ject is at present in a state of great confusion. Such differences
as depend on minute variation in the configuration of the cranium
and in the conformation of the teeth can only be dealt with by
some one with technical knowledge and considerable practical

2 A SHORT NOTE ON THE INDIAN RATS.

experience, and accordingly they will not be considered in this
paper. The subject of body measurements will be gone into fully,
as fresh measurements made by the man on the spot are the only
ones that are of any use, owing to the very great tendency to
shrinking and distortion in preserved specimens. Coloration will
also be dealt with, as this again is better noted in the fresh speci-
men, as dried skins are apt to change in colour and minute points
of difference to become obscured in spirit specimens. The pre-
servation of specimens in spirit and other media, the preparation
of dried skins and skulls, the proper labelling and noting of
specimens, will also be gone into, and finally a short description
will be given of the rats which, so far as is known at present, are
probably of practical importanee as propagators of plague.

BODY MEASUREMENTS.
The most important measurements are only four in number—

(1) Length of head and body.
(2) Length of tail.

(3) Length of hind foot.

(4) Length of ear.

They are most accurately taken by sliding callipers, but quite
useful results can be obtained by means of a measuring tape,
particularly a steel tape, or a pair of compasses and a measuring
rule or tape. The measurements should be recorded in centi-
metres and millimetres, and for the convenience of those who
have only an English scale to work from, a table is given at the
end of this paper for the ready conversion of English into metric
measurements. The length of the head and body is taken from
the tip of the nose, excluding hairs, to the centre of the vent.
The body should be straightened out, particularly if rigor mortis
is present, and if a tape is used care must be taken that the tape
is straightened and not allowed to follow the curves of the body.
The length of the tail is taken from the centre of the vent to the
tip of the tail, excluding hair. The length of the hind foot is
taken from the point of the heel to the tip of the longest toe,
excluding the claw; the foot must of course be straightened. Any
abnormality in the pads of the foot, normally five in the forefoot
and six in the hind foot in the common species, should be noted.
The length of the ear should be taken from the lowest point of
the external orifice to the tip, excluding hair.

PREPARATION OF SKINS.

If fresh measurements have been taken, dried skins and skulls
are the most valuable material and are very easily packed and
sent to their destination ; skins without measurements are of very
little use, as they get stretched out of all proportion. No time
should be lost in skinning, as putrefaction in India may come on
an hour or two after death. ‘The only parts likely to cause trouble

A SHORT NOTE ON THE INDIAN RATS. 5

are the feet and the tail. When about an inch of the tail has
been skinned back the reversed portion should be firmly grasped
with a duster or any old rough piece of cloth; it will generally be
found that the skin will slip off quite easily hike a glove from a
finger. In large, thick-skinned rats like the bandicoot, in which
the skin is very adherent and threatens to break, it may, however,
be necessary to slit the tail on the lower surface and dissect the
skin off.

In the hands and feet the skin must be reversed right back
to the fingers and toes and the flesh scraped off the bones of the
palms and soles. It will be found impossible to get the skin
back over the limb unless a string has been previously tied to
the toes or fingers. The limbs should be disarticulated at the
hip and the shoulder and the bones roughly cleaned with a knife.
The slit in the belly should be kept as small as possible. Pow-
dered alum should be well rubbed in, with particular attention
to the feet and tail; or if this is not available wood ashes may
be used. The muzzle, ears and the feet should be brushed over
with a little strong carbolic of a strength of one in three. Two
er three days willbe found sufficient to train any dém to skin
perfectly well.

PREPARATION OF SKULLS.

The very first thing is to secure a label with a number cor-
responding to the skin; I have had constantly to reject skulls
owing to skinners neglecting this precaution. It is most con-
veniently affixed by means of a needle and thread passed under
the zygoma, the arch of the cheek bone. Ina young skull in
which the arch is incomplete, the thread must be passed right
round the skull. The skull is boiled for some hours and then the
brains and remaining flesh are removed with a piece of turnedup
copper wire, a crochet hook or the like. It should always be
insisted that the skinner should remove part of the neck with the
skull; unless thisis done he is lable to cut away the back part
of the skull, rendering it useless for purposes of measurement. He
must also be cautioned not to damage the back part in removing
the brains through the opening for the spinal cord. The lower
jaw should be secured to the skull with thread.

PRESERVATION OF SPECIMENS.

Spirit is the most reliable medium in which to preserve
specimens, if skins cannut, for any reason, be prepared, but no
time must be lost after the animal has been killed, or putrefac-
tion may proceed even in the spirit, and plenty of spirit must
be used. The amount of spirit used is most important. If the
bodies of the rats occupy more than half the receptacle so
much of the spirit gets absorbed by the tissues that the remain-
ing fluid is too weak to prevent putrefaction. To pack rats
into a jar and then fill up the interstices with spirit, as 1s

4, A SHORT NOTE ON THE INDIAN RAT'S.

frequently done, is absolutely useless. The best way to make cer-
tain of avoiding bad results is to keep the rats in a large bulk of
spirit for about a week They can then be transferred to a
smaller receptacle more suited to packing and postage. It is
well to add to the spirit carbolic in the strength of 1 oz. to the
pint, and the belly should be slit open to allow of penetration of
the preservative medium. A_ giass-stoppered bottle is the best
receptacle ; the stopper should be luted with soft paraffin or seal-
ing wax or pitch. Screw-topped jam jars will do, or for large
consignments a kerosine tin may be soldered up, care being
taken that the soldering iron is not too hot. Formalin may be
used, but it must be remembered that in India weak solutions
are absolutely useless; time and again I have received tins that
contained little better than formalin rat soup. As the result ot
experiments I think that nothing under 15 per cent solution ot
formalin is to be depended upon in India, particularly with large
and thick-skinned rats. This is equivalent to 6 per cent of formic
aldehyde, as formalin, the commercial preparation, is a 40 per
cent solution. Even with this strength it is necessary that no
time should be lost between the death of the animal and its
immersion in preservative.

Formalin is volatile, so the same precautions should be
observed in sealing up as in the case of spirit. Specimens in the
former preservative should not be kept for long in tins.

LABELLING SPECIMENS.

It will be found of the greatest service if a register 1s kept of
all rats forwarded, or in other words of all rats measured, as skins
or spirit specimens without fresh measurements are of compara-
tively little use. The register might be as follows :—

|

Register No.

| Date of collection.
Locality (with altitude .
Length of head and body
Length of tail.
Length of hind foot.
Length of ear.
Number of teats

|} Remarks.

The date of collection is important as an index to seasonal
changes of coat; the number of teats is rather important, as the
number and distribution vary in different species. The most:

a

A SHORT NOTE ON THE INDIAN RATS. 9)

convenient form of record is exemplified as follows :—#2; the upper
figure means 2 pairs of pectoral or breast teats while the lower
figure means 3 paws of abdominal teats. An asymmetrical
distribution may be indicated as follows—2-+ 3, the teats of the
right side being given first. A ticket with the register number, or
still better a ticket with number and full measurements, should
be attached to the rat before it is handed over to the skinner,
with a duplicate ticket for the skull. The method of labelling of
the skull has already been described ; the material of the skull
label is important as the skull has to be boiled. Tin foil which
is quite soft and can be easily perforated and scratched is best ;
lead or a piece of ordinary biscuit tin will do. In the column for
remarks it should be stated whether the rat is found dying in
numbers in the plague season, 2.¢., whether 1t suffers from plague,
if positive information on the subject is available.

The advantage of the register is that in case of a label becom-
ing partially destroyed or illegible a reference to the register is all
that is required. The advantage of the fully written up label is
that a huge amount of work is saved at headquarters.

YOUNG RATS.

Considerable difficulty may be caused to the beginner if he
does not know how to recognize a young rat, as its general
appearance(andiproportions may differ considerably from that of
the adult. The coat tends to be grey and furry, almost mole-like,
owing to the grey underfur showing up through the longer hairs;
for the same reason the belly is much darker than in the adult.
The head is proportionately large, but the foot is a much more
certain and easily recognized guide. It may be relatively almost
twice as large as in the adult. The rule may be laid down that
if the hind foot is as much as 30 per cent of the length of the
head and body, the rat is a very young one, only just cutting its
third molar, and has only attamed 50 or 60 per cent of its full
length. In the full grown adult the hind foot is only about
20 per cent of the body length, and in an exceptionally large and
old specimen may be as low as 16 per cent. In some of the
Nesokias the foot may be very large even in the adult (as much
as 25 per cent), so that the rule has to be somewhat modified, but
this is a point on which more information is required, particularly
as to the size of the foot in immature specimens.

COLORATION.

The coloration of rats is a character on which considerable
stress has been laid asa means of differentiation, much more indeed
than is justified. A large number of rats have very much the
same colour, and the minute differences that are sometimes
described are vitiated by the fact that the great range of colour
which may be present in ditterent dividuals of the same species

6 A SHORT NOTE ON THE INDIAN RATS.

has been insufficiently recognized. It therefore becomes all the
more important that accurate observations should be collected as
to variations normally found in different species in different
localities. This is not quite such an easy matter as might at first
sight appear, as nothing is more difficult than to describe accu-
rately the tints and shades of tints to be found in the fur of an
animal. To meet this difficulty a scheme of standard colours has
been drawn up, known, by the name of its inventor, as “Ridgway’s
Seale of Colours for the Use of Naturalists”; a few of the colors
which are most commonly mentioned in standard descriptions of
rats have been reproduced, by hand in the plate. When the full
scheme is used for reference the difference between the shades
will be found so fine that it is no easy matter to decide which
name to use to describe the particular colour under observation.
Those who are accustomed to the use of colours, particularly water
colors, are advised to refer to shades in terms of ordinary paints
and to describe the animal as one would paint it. “Rufous” and
“yufescent” are terms constantly used, but not in the strict sense
of Ridgway’s scale.* “Rufous” means a foxy red, “rufescent”
brown with a tendency to foxy red. The light red which gives the
“rufous” of Ridgway’s scale is rarely seen in an animal’s coat.

INDIAN RATS CONNECTED WITH PLAGUE.

Our knowledge of the rats that play an active part in the
propagation of plague is at present so deficient that it is quite
impossible to give any satisfactory account of them. At the same
time nothing is more likely to assist in the collection of the desired
information, or to lighten the labours of the inexperienced obser-
ver, than a succinct account of the rats of common occurrence and
likely to prove of interest and importance to the practical epi-
demiologist. There are many species which are of very rare
occurrence, of which only a few specimens are known, and which, in
spite of their great interest to the zoologist, need not be considered
at all by the epidemiologist. These, exemplified by Mus blan-
fordii, Mus bowersi, Mus berdmorei, Mus fulvescens, I shall leave
out of account altogether. There ave others, mainly field-rats,
which, from their habits and distribution, probably play only a
negligible part in the upkeep and spread of plague. These cannot
be neglected altogether in view of the warning already given in
the case of Nesokia bengalensis, a rat which on the strength of
its being a field-rat has been left out of account altogether not
only by the epidemiologists but also by the zoologists to whom
they appealed. This rat has nevertheless been shown to be of
great practical importance in Calcutta. Accordingly I shall give
a brief mention of the most important of those rats with no
attempt at a full deseription. The third category is that of the
rats which are known to be the chief factors in the spread of plague

* In Ridgway’s scale ‘‘fulvous ’ and “tawny ” are regarded as synonymous terms.

A SHOR "! NOTE ON THE INDIAN, RATS. uf

and of one or two which are house-rats of sufficiently wide dis-
tribution and common occurrence to make if important that they
should be definitely recognized. Of these a short account will be
given, non-technical as far as possible, but sufticiently full to make
their identification a simple matter. Mice I shall leave out of
consideration altogether, as although J/us musculus has been
found infected in Australia, and although I have, as a rare excep-
tion, found mice dying of plague in Calcutta, I consider them of
very littie practical importance. The third category as the most
important will be the first to be dealt with and will comprise the
following :—

Mus rattus, the Black Rat.

Mus decumanus, the Brown Rat.

Nesokiw bengalensis, the Indiun Mole Rat.

Nesokia baundicota, the Bundicoot Rut.

Nesokia hardwickit, the Short-tailed Mole Rat.
Mus rattus var. nitidus, the Hill House Rat.

Mus concolor, the little Burinese Rat.

Mus and Nesokia are two closely allied genera of the sub-family Murine be-
longing to the family Muride. The chief distinction between Nesokia and Mus may
be broadly put as follows: the former are stout, heavily built rats with short, heavy,
broad heads, an arvicoline or vole-l:ke aspect, lar. 2e feet and large molars in which

the division of the tooth into transverse lamine is much more ainarked than the
division ef the sinuous lamin into cusps as it is found in Mus.

1. MUS RATTUS—THE BLACK RAT OF ENGLAND.

This 1s the common house-rat of India and the rat that is
the mest important in the propagation of plague, as from its habits
it is brought into very intimate contact with man and is accord-
ingly more liable than any other to infect him through the
medium of its fleas. 1t is a slender rat with a very pointed muzzle,
large out-standing ears, large prominent eyes anda long tail,
_as a rule 25 per cent. longer than the head and body. The feet
are of medium size but comparatively long and slender. In size
it is very variable, ranging from 14 cm. to 19 cm. in length of
head and body. In color it is very variable also, but the most
common type is a rather light rufescent brown with a white or
grey belly. The grey of the belly may be orange-grey or sprinkled
with fawn, and the white may be marked with a central stripe or
spot of grey. Sometimes the whole coloration of the1at may be
darker en usual, and the darkening may go so far that it is
black. ‘This occurs in 30 per cenit. of those found in Bombay, but
in Calcutta melanotic forms are rare. On the other hand, the
colour may be much lighter than usual,—a pale yellowish or
cinnamon-brown, and this may be so extreme that the rat is found
yellowish, greyish or almost white. Though essent’a'ly a house-
rat, living typically in the tiles of the roof, in the thatch, in holes
in the floor, recesses behind boxes and such like places, 1t may be
arboreal in which case it tends to be more slender, smaller and

TED OPE GO NS

8 A SHORT NOTE ON THE INDIAN RATS.

lighter and more rufescent in colour.. Two distinct varieties have
been described, — alexandrinus, larger, heavier and typically found
in Northern India, and rufescens, smaller, redder and typically
found in Southern India. Recent work particularly in Calcutta
seems to indicate that no sharp distinction can be drawn between
the varieties, as both occur together and intergrade completely.
Accordingly the name Mus rattws has been used and the terms
alecandrinus and rufescens have been dropped altogether. The
tail is uniform brown and regularly annulated; a white tip is
exceptionally found. The teats are 3. The distribution is pro-
bably cosmopolitan, ranging up to 8,000 feet according to Blanford.
This rat is almost solely responsible for the plague of Upper
India, as far as is known at present.

2, MUS DECUMANUS—THE BROWN RAT.

This is the brown rat of England, a sewer and ship rat
probably introduced from Europe, though there are some that hold
that its original home is China. It is confined mainly to ports
and is, so far as is known, comparatively rare inland. It is a large
heavy rat which may be distinguished by its bi-coloured tail,
which is distinctly lighter below, its large heavy flesh-coloured feet,
its short, round ears and broad heavy-jowled head. It is brown in
colour, becoming grizzled below and fading off into dirty white
on the belly. The ears generally fall short of the eye when laid
down along the face, whereas in Mus vattws they generally cover
the eye. The tail is heavy, uniformly tapered and averages 89
per cent. of the length of the head and body. The most common
formula of the mamme is 4. Though a burrowing, drain-frequent-
ing rat it is frequently captured in the upper storeys of houses.
It exceptionally reaches a very large size in Calcutta,—as much
as 11 inches in length of head and body, practically the size of the
bandicoot. The different shape of its head and the comparative
smallness of its foot will distinguish it. This is the rat most
frequently affected by plague in Bombay.

3. NESOKIA BENGALENSIS—THE INDIAN MOLE RAT.

This has been in the past very frequently confused with the
preceding rat, as in size and general appearance it is not unlike
is. It is however a much more coarsely furred rat, the underfur
being so thin that the naked skin can frequently be seen when it
is enraged and erects its fur. The back is covered with very long
black bristles 4—5 cm. in length, which are quite characteristic.
When trapped it is generally very savage in demeanour, bristling
its coat, spitting and snarling at one. The head and neck are
short and thick and the whole body is stout. In colour it isa
colder greyer brown than the brown rat and fades off to a dirty
rusty white on the belly. ‘he tail is characteristic, beiny rather
shor (81 per cent. of the length of the head and body), uniformly

A SHORT NOTE ON THE INDIAN RATS. 9

brown, and distinctly attenuated at the tip. A glance at the foot
will settle the question if there is any doubt, for it is relatively
small, is not flesh coloured and the pads are characteristic. Instead
of being large and prominent and as a rule heart-shaped as is
found in the black and brown rat, the pads tend to be small and
circular ; that nearest the heel on the outside is small indeed, not
infrequently it is wanting altogether, so that the usual six pads
are represented by five. Occasionally the medium pads may be
heart-shaped; in such the rudimentary condition or complete
absence of the sixth pad will give the clue to identification. Though
originally a burrowing field-rat which stores grain in its
complicated burrows, in Calcutta it is found infesting stables,
grainshops, and such-like places; it is capable of piercing even
cement and brick. The mammz are numerous, the most common
formula being 4 or 4. Its distribution is very wide, as it is found
over the greater part of the Indian Peninsula from the base of the
Himalayas to Cape Comorin, and from Lower Sind to Cachar and
Assam; it is more common in damp alluvial tracts but ascends to
the top of the Nilgiris and other hills. It is found also in Ceylon
and the valley of Kashmir, and apparently throughout Burma to
the Mergui Archipelago. This is the most important plague rat
in Calcutta; in both this city and in Dacca it accounts for about
half of the total rat population.

4. NESOKIA BANDICOTA—THE BANDICOOT RAT.

Its excessive size makes it difficult to make any mistake as to
the identity of this rat. It has occasionally been confused with
very large specimens of the brown rat, but its extremely large,
blackish feet, with foot pads as in the mole rat, should at once
distinguish it. It has the same colour, the same bristly coat,
and savage demeanour as the latter. Its head is different from
that of the brown rat, as is shown in the sketches, being narrow
and deep-muzzled like that of a greyhound. So far as is known,
it is not generally liable to be attacked by plague. It is found
all over the Peninsula of India and Ceylon. It is said not to be
found in Sind or the Punjab, though common in Rajputana,
the N.-W. Provinces and Bengal. The form found in Bengal is
a smaller northern variety (nemcrivagus) which is found also in
Burma and the Eastern Himalayas; the southern form is larger
and runs up to 30 em—37:5 cm. in length with a tail of 27-5
to 32:5 cm. and.a hind foot of 6:25 cm. It is a burrowing,
grain-storing rat.

5 NESOKIA HARDWICKII—THE SHORT-TAILED
MOLE RAT.

The main reason for including this rat is that it has been
sent for identification from Bihar in connection with plague
operations. It is so purely a field-rat that it is doabtful whether
it is of any importance. It has very large feet and a very broad,

10 A SHORT NOTE ON THE INDIAN RATS.

round head. Its colour is yellowish to rufous brown above with
a hoary grey or white belly. The fur variesin texture but tends
to be long and soft. There are two varieties—hattoni, a soft-
furred form witn large feet found at high elevations in Baluchistan
and Afghanistan and the typical form with darker, harsher fur and
sinaller feet, found in N.-W. India.

6. MUS RATTUS, VAR. NITIDUS—THE HILL HOUSE RAT.

This differs from the Mus rattus of the plains in that the tail
is much shorter, almost the same length as the head and body,
and the fur, as might be expected, is much longer and_ thicker.
The flea found on this rat in Darjeeling is not Pulex iwrituns
but Ctenopsyllu muscult.

7. MUS CONCOLOR—THE LITTLE BURMESE RAT.

This is really a miniature Mus rattus. It has been included in
the list of descriptions because it is the common house-rat of Burma
and probably plays an important part in plague in that country.
The colouring is the same as that of Mws rattws except that the
belly is generally pale brown instead of white, grey or orange-grey.
It is rather mouse-like in size but is structurally a small rat.

Amongst the field rats which prebably are of very little
importance, the commonest have already been described with the
house-rats, as they are more liable than most to be found away
from their proper haunts, namely, the Nesokias. The Gerbilli, of
which the most common and well-known species is G. indicus,
is too characteristic and too well known to require description.
It is commonly called the antelope rat from the powers of leaping
which it possesses ; 1ts excessively long feet, large ears and very
long tufted tail make it easy of recognition. Mus mettada, the
soft-furred field-rat, 1s more like a large mouse than a rat, and
can be at once recognized from the fact that it has only four or
five plantar pads, generally four. It is found in most parts of
the Peninsula of India and also in Sind. The musk-rat or the
grey musk-shrew, Crocidura cerulea 1s not a rat at all but is one
of the insectivora and does not seem lable to plague. Amongst
the many other animals which are exceptionally attacked by
plague none are worthy of mention together with the rats, except
perhaps the squirrels. Where thatched roofs are the rule the
squirrels may be as great a domestic nuisance as their first cousin
the rats, and the former are apparently frequently attacked by
plague, so that in some places they may be a factor of practical
importance. Only two species need be considered—Funambulus
puwlmarum, the palm-squirrel or common striped squirrel, and
Funambulus tristriutus, the jungle striped squirrel. They are
easily distinguished, as in the former the three pale dorsal stripes
are broad and are so supplemented by the light colour below the
lowest dark intervening stripe that the species might well be
described as possessing five light stripes. In the jungle form the

A. SHORT NOTE ON THE INDIAN RATS. i

three stripes are very narrow and are not supplemented by an
ill-defined lower pair; this form may be found in houses where the
domestic form (the palm squirrel) does not exist.

Throughout this pamphlet my endeavour has been to keep
the language simple and free from technicalities ; accordingly there
have been no references to the history or literature of the subject;
no discussions on disputed points ; no mention of cranial measure-
ments. Those who wish for information on such points are referred
to my Memoir on the Rats of Calcutta, now being issued as part
of the first volume of the ‘“‘ Memoirs of the Indian Museum.”

CALCUTTA : Wm. C. HOSSACK, M.D.,
17th March 1907. Plague Department.

TABLE OF AVERAGE MEASUREMENTS.*

Head and body. Tail. Foot. Ear. Remarks.
Mus concolor speed 12 2°25 1:25 Miniature M. rattus.
Mus mettada sons 12S) 10°5 25 1:85 4 pads. Mouse-like.
Gerbillus indicus ono ts 18 3°75 15 = 4 _ pads. Tufted tail.

212 House rat with long

Mus rattus ... ooo 17:3 20°97 3°31 ears and tail.
Drain rat with short
Mus decumanus . 22°6 20:2, 4:15 1:97 ears and bicolour
tail.
Hill house rat,
Mus rattus var. nitidus ... 185 185 636 2°16 Long ear, medium
tail,
Short attenuated
Nesokia bengalensis eso 2 14:79 3:19 1:95 tail, small round
{ pads.
Nesokia hardwickii we SRD 11 300 1:25 Tail very short.
Nesokia bandicota noo | ADS) 25:5 5:1! 27 Largest Indian rat,

TABLE FOR CONVERSION OF INCHES TO CENTIMETRES.

Inches Centimetres. Inches. Centimetres. Inches. Centimetres.

A 15 Qs 6:25 7% 18°75
Pt 3 3 75 8 20

a 6 32 8°75 gh 21:25
& 1-25 4 10 9 22:5
8 21 43 11:25 92 93-75
2 1:66 5 12:5 10 25

a 22 5B 13°75 103 26 25
1 D5 6 15 11 27-5
13 3:75 64 16:25 113 28.77
2 5 7 17-5 12 30

* All the measurements are in centimetres,

2252 —’07.

Indian Rats (Ind. Mus.) Priare I.

re
~ ore I
= ~~ me
SSS - SES
S&T
SS< on ies

bres Ie Fie. 2.

\ TD |, Wy iM
Aha I LEA

| iM Hah
\ i

WAS | ins: Mf
a Sie
\ rts ye

Fies. 1 & 4—Mus decumanus.
Fie. 2—Mus rattus.
Fig. 3—Nesekia bandicota var, nemoriwaqus.

All natural size.

Indian Rats (Ind. Mus.) Prats II.

Fie. 8.

Fic. 5—Right hind foot of WV. bandicota.

Fig. 6— Ditto of M. decumanus.
Fie. 7— Ditto of N. bengalensis.
Fie. 8— Ditto of M. rattus.

All the figures life size except Fig. 5, which is slightly reduced.

SPECIMEN COLOURS

(AFTER RIDGWAY)

FULVOUS FAWN . BUFF

RUFOUS | CHESTNUT

ISABELLINE OCHRACEOUS. BURNT SIENNA

Tio NI

3 2044

BPs ke
iy

d