THREE NEW MAMMALS FROM SIAM. 75 
seem, however, related to it, and it is the earliest, undoubtedly allied 
race, I am able to compare them with for the moment. 
For comparison, the dimensions of the type of R. rubricosa 
(Anderson, Zool. Res. Yunnan, p. 306) from the country between 
Bhamo and Momein, are given: though also a grey-bellied rat, it will 
be seen that it isa far smaller animal; the skull of R. g. rahengis is 
heavy with strong ridges whereas the other’s looks more like that of a 
gigantic RP. concolor. 
Measurements of Rats in millimetres. 
; — 
: : evs. 
3% So 25 a 
= = 28 3 
&-2 S$ -2 ss S 
vo D ‘a D See es = 
= s = nS = 2 ro 
as SS a q 
aes 5 ; Ss : 
xs &S & RS 
Head and body ... eee oma oO 208 205 140 
Tail sae eee ane eos} 174 194 190 130 
Hindfoot, s.u. oe ae: 34 37 35 32 
Kar eee eee eee 19.5 21 20.5 a 
Skull :-— 
greatest length ... eee ose 44.3 45.2 45 37.5 
condylo-basilar length ... one 38 39.8 ayy oh aod 
palatilar length oe coef 22 20.8 17.5 
diastema eee oan ate 12 12.5 12.4 10 
upper molar row (alveoli) sas 7 | (e 6.8 6.8 
combined palatal foramina ...| 8.1 x 2.8 8.92.8} 8.63) 7.3 x 2.2 
m3—m3 (alveoli) ase veel 5.1 5.3 5 4.1] 
nasals ess ons ee} 1I8X5 | 18.55] 16x5 | 14.8x4 
interorbital breadth ... dis Gi | 6 6.7 5.4 
brain case breadth oe jae 17 17 16.5 15.7 
zygomatic breadth wee eo] 20.8 20:R. |e 204 17.2 
3. Rattus rajah siarma, subsp. nov. 
Rattus surifer, Gyldenstolpe (partim), Kungl. Sv. Vet. Akad. Handl., 
57, No. 2, p. 42 (1917) [Koon Tan, N. Siam]. 
Type. Adult male (skin and skull) from Sikawtur, 40 miles 
“Male with very worn teeth from Plentong River, S. Johore, Malay 
Peninsula, No, 2539-08. F. M.S. Mas. 
7 Teeth considerably more worn than No. 2637, slightly more worn than — 
No. 2368. 
VOL. III, NO. I, 1918, 
