66 Journal of the F.M.S. Museums. [Vol. 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, 355 (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 ot type: greatest length, 44-4 

 (44'o) ; condylo-basilar length, 39-0 i'39'o) ; diastema, 12-4 

 (i2 - g) ; zygomatic breadth, 20'o (20 - i) ; median length of 

 nasals, i6'0 (16-3) : upper m<>lar series. 6"8 (6*9). 



Extremes of twelve specimens; greatest length. 4i'5-44"4; 

 condylo-basilar length, 36'3-39'o; diastema. n - 6-i2"6; 

 zygomatic breadth, i8"8-2r2: median length of nasals, 

 i4 - o-i6'i ; upper molar series. 6-5-7-2 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 orang hint people inhabiting the island are fairly 

 uniform, the principal variation being in the degree of 

 distinctness in t lie line of separation of the light undersurface 

 from the flanks. The race closely resembles a form, as vet 

 un-named, inhabiting the western islands of the Archipelago 

 but appears to be somewhat mure robust. The intrusion in 

 the central islands of a race, R. r. rhionis which closely resem- 

 bles the north European R. rattus rattus is a curious and 

 as yet unexplained fact. 



'Mus rattus rhionis, Tbos & Wrought Ann. and Mas. 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. 2086/0S. 



