66 Journal of the F.M.S. Museums. [Vot. VII, 
RATTUS RATTUS BATIN, subsp. nov. 
Type :—Adult male, aged (skin and skull). Collected at 
Mentigi, West side of Pulau Mapor or Panjang, Rhio Archi- 
pelago, on June 6th, 1915, by H. C. Robinson. Federated 
Malay States Museums No. 304/15. 
Characters:—A member of that section of the Epimys 
rattus group, characterized by somewhat slender feet, hispid, 
but not very spiny pelage and marked development of long 
black piles on the lower back. Separable from the form * 
inhabiting the adjacent islands of Bintang and Battam by the 
very much lighter colour above and by the somewhat larger 
bullae. 
Measurements :—External dimensions of the type, taken 
in the flesh: head and body, 208 (180); tail, 218 (195); hind- 
foot, 35°5 (34), ear 22 (20°5). Extremes of eight specimens, 
head and body, 171-208; tail, 193-218; hindfoot, 33°5-35'5; 
ear, 20-22. . 
Cranial measurements of type: greatest length, 4474 
(44°0); condylo-basilar length, 39°0 (39°0); diastema, 12°4 
(12°9); zygomatic breadth, 20:0 (20°1); median length of 
nasals, 16°0 (16°3) ; upper molar series, 6°8 (6°9). 
Extremes of twelve specimens; greatest length, 41°5-44"4; 
condylo-basilar length, 36°3-39'°0; diastema, 11°6—-12°6; 
zygomatic breadth, 18°8-21'2; median length of nasals, 
14°0-16°1; upper molar series, 65-772 mm. For detailed 
measurement see table on p. 69. 
Specimens examined :-—Fifteen, from the east and west 
sides of Pulau Mapor. 
Remarks :—The series examined, which was trapped both 
in old jungle and in the vicinity of the huts of the some what 
primitive ovang laut people inhabiting the island are fairly 
uniform, the principal variation being in the degree of 
distinctness in the line of separation of the light undersurface 
from the flanks. The race closely resembles a form, as yet 
un-named, inhabiting the western islands of the Archipelago 
but appears to be somewhat more robust. The intrusion in 
the central islands of a race, R. r. rhionis which closely resem- 
bles the north European R. rattus vattus 1s a curious and 
as yet unexplained fact. 
* Mus vattus rhionis, Thos. & Wrought. Ann. and Mag. Nat. Hist. (8) iii, 
P. 441 (1909). Measurements in parentheses are those of an adult male 
topotype of Mus rattus rhionis, Thos & Wrought. F.M.S. Mus. No. 2086/o8. 
