1907.] DR- Hossack : The Rats of Calcutta. ig 



this is white on the belly, but occasionally it is only the tips that are white. On the 

 body the grey underfur is frequently tipped with pale yellow or ochraceous buff. The 

 underfur varies with the general degree of pigmentation, and in dark rats is a very dark 

 blue-grey and in black rats may be almost black. 



2. Hairs of i-i"25 cm. long, as a rule grey below with the brown or black upper 

 part terminating in a tip of ochraceous orange. Other hairs have no brown or black in 

 the upper part. It is the predominance of these ochraceous or orange hairs which 

 determine the lightness of colour and rufescence of the rat. These are the hairs which 

 are often replaced by whitish or grey spines with black or brown tips. 



3. Long black hairs in the dorsal region, particularly over the rump. — These 

 vary from 2-25 to 25 cm. in length but are comparatively fine and need not be mis- 

 taken for the huge coarse bristles of Nesokia. Occasionally they are much longer than 

 stated, and may run up to 3 to 4 cm. in very large coarsely furred specimens.^ 



Tail. — The tail is long and slender, averaging about 125 per cent, of the body- 

 length ; the artist has made it rather thicker than it should be. It varies, however, 

 within considerable limits, and shows a tendency to be longer in the smaller rats, so 

 that the true average line slopes from 135 for rats under 15 cm., down to 120 for large 

 rats of 19 cm. and over, with extreme limits of 152 and 106 per cent. The tail is 

 uniformly tapered and very regularly annulated, the rings averaging in the centre of 

 the tail 10 to the centimetre. The tail is scantily clad with brown or black hairs as 

 long as the depth of two rings. Towards the tip the hairs are longer, but they do not 

 form a brush. In colour it is generally uniform blackish brown, but if the rat is a light- 

 coloured or rufescent one, the tail may be pale madder-brown. Thomas and Blanford 

 make it faintly lighter below. I find as a rule that it is absolutely uniform and 

 only very occasionally does one get a faint trace of lightening underneath. 



White tips. — Four times I have found white-tipped tails, in addition to noticing on 

 two or three occasions that the four or five longer terminal hairs were white. In 

 three instances the effect was marked as both skin and hairs were white ; in two of 

 these the tip was 2 cm., but in the third it was only 0-2 cm. long. In the fourth instance 

 the last 5 cm. of the tail were covered with white hairs, but the skin was brown, so 

 that the general appearance was as if the end of the tail had been dusted with 

 flour. This white tip was noted as a sport in Nesokia bengalensis also. 



Whiskers. — These are very long, longer than the head and ear combined. The 

 lower two or three vibrissae as a rule are white, the rest black. The tips are frequently 

 lighter. Two, or sometimes more, very long cilia spring from the supraorbital 

 region. 



Feet. — Both fore and hind feet are, as a rule, covered with short, white hairs, and 

 their sides are flesh-coloured. In dark rats the middle of the hind foot will be light 



' I have attempted as far as possible to describe the hair colour by comparison with Ridgway's scale 

 of colours, but I find it a most unsatisfactory process, as a single hair may require half a dozen long and 

 unfamiliar names to describe it. Take a long black hair which shades down to white or almost white at 

 the base. From black one works through two or three varieties of brown, next through two or three 

 shades of drab, passing through isabelline to delicate changes of grey before white is finally reached. 



