A FOURTH COLLECTION OF SIAMESE MAMMALS. 63 
house-rat: underparts much washed with buffy in both. 
Measurements :—-head and body, 115, 115; tail, 147, 141; hind 
foot, s.u, 27, 25; ear, 15,16. Skull (male only) :—greatest length, 
31 ; condylo-basal length, 27; palatilar length, 14.4; diastema, 8.4; 
upper molar row (alveoli) 4.9 ; length of palatal foramina, 5.2; length 
of nasals, 13; interorbital breadth, 4.8 ; breadth of braincase, 13.3 ; 
zygomatic breadth, 15 mm. 
22. Rattus rattus thai. 
Rattus rattus tha’, Kloss, Journ, N.H.S. Siam, IT, p. 286 (1917). 
Mus rattus, Bonhote, P. Z. 8. 1900, p. 194; id. op. cit. 1901, vol. 
Ty p- 56. 
2 ¢ ad, 3 d subad., 3 2 ad., 2 2 subad. from Sikawtur and Me 
Taw, N. W. of Raheng, W. Siam, 1500 ft [Nos 2639-45, 2666-8/ 
CBK.]. Collected by Mr. K. G. Gairdner between 3 Feb. and 3 July 
1917. Orig. Nos. 355,6 ; 360,1 ; 375, 330, 458. 
A typical series of the Northern Siamese common rat, rather 
brighter above than R. r. neglectus of the south and with twelve, 
instead of ten, mamme in the females. 
“The rutting season seems to be January—February.” Of July 
examples Mr. Gairdner notes: ‘‘ Reappeared after the hot weather.” 
(For measurements see table postea). 
23. Tautatus thai. 
Kloss, Journ. Nat. Hist. Soc. Siam, II, p. 280 (1917). 
1 o ad. from Me Taw, 1500 ft, 40 miles N. W. of Raheng, 
Western Siam [ No. 2617/CBK.] Collected on 9 Feb. 1917, by 
Mr. K.G. Gairdner. Orig. No. 369. 
Pelage spineless, composed above of coarse and fine hairs, the 
stiffer tipped with black, the softer with bright ochraceous-buff; the 
general colour effect of the upper parts being ochraceous-buff finely 
streaked and lined with black, the latter diminishing in quantity on 
the sides: base of upper pelage deep neutral grey. Hands and wrists, 
feet and entire under-parts white apparently fairly clearly margined, 
the fur of the under-parts distinctly dark grey at base. Tail dark 
above and paler below, the hair clothing it in agreement. 
Nasals extending just within the line of the orbital spaces and 
not exceeded posteriorly by the premaxillaries. Anteorbital plate 
markedly convex, the lower part of the edge vertical. Palatal for- 
VOL. III, NO. 11, 1918, 
