62 MR. C. BODEN KLOSS ON 
all round. Base of hair on upper parts neutral grey, of dorsal spines 
pale with a greenish tinge. 
Native collector’s external measurements :—head and _ body, 
134 (140)*; tail, 164 (159) ; hind foot, s.u., 29 (26); ear 24. 
Skull :—greatest length, 36 ; condylo-basal length, 31.4 (31.4); 
condylo-basilar length, 29.8 ; palatilar length, 15.2; diastema, 9.1 (8.3); 
upper molar row, alveoli, 6 (6) ; nasal length, 13.4 (13) breadth com- 
bined nasals, 4; palatal foramina, 6 x 2.3; greatest breadth of rostrum 
6 (6.2); length of rostrum from upper rim of ante-orbital foramen, 11.8 
(11.4); interorbital breadth 5.3 (5.8); zygomatic breadth, 16 (16.3). 
The palatal foramina fall short of the molar roots by nearly a 
millimetre. 
Rattus marinus mihi, from Koh Chang and Koh Kut, Chantabun 
Archipelago, S. E. Siam,f will probably prove to be a subspecies of 
lepidus when more of the latter have been compared with it. A series 
only differs from the present animal in having the feet less completely 
white, while in the skulls, the nasals are narrower posteriorly and the 
diastema is longer (lepidus 8.3—9: marinus 9.2—10.1 mm.). 
Rattus lepidus and marinus are members of a group of rats easily 
separated from other species of the same general colour by the pale 
green bases of the dorsal spines. Some other continental animals 
belonging to it are 2. bukit (Bonh.) and R. orbus (Robinson and Kloss) 
from Peninsular Siam and &. cremoriventer (Miller) from the same 
area with its subspecies I. c. tenaster (Thomas) from Muleyit, Tenas- 
serim ; the two last, however, form a distinct section of the group a§ 
the tail is more hairy and brown throughout, not white below. 
21. Rattus concolor. 
Mus concolor, Blyth, Journ. Asiat. Soe. Bengal, XXVIII, p. 295 
(1859) ; Bonhote, P. Z. S. 1900, p. 195 ; id. op. cit. 1902, vol. 1, p. 
39; Gyldenstolpe, Arkiv for Zoologi, 8, No. 23, p. 18 (1914). 
Epimys concolor, Kloss, P. Z. 8. 1916, p. 57. 
Rattus concolor, Gyldenstolpe, Kungl. Sv. Vet, Akad. Handl. 57, No. 
2, p. 45, pl. VI, figs. 5, 8 (1917). 
1 d,1 2 vix ad. from Raheng town, Western Siam, 450 ft. [Nos. 
2680, 1/CBK.]. Collected by Mr. K. G. Gairdner, 
Two large specimens with unworn teeth of the little spin y 
* Measurements in parentheses those of the type—also an adult female 
tEpimys jerdoni marinus Kloss, P. Z. 8. 1916, pp. 50, 72. 
JOURN. NAT. HIST. SOC, SIAM. 
