N. GYLDENSTOLrE, MAMMALS COLLECTED IN SIAM. 17 



only a single specimen of this species, which was trapped in 

 a brush-jungle near Sakerat on the lOth of January 1912. 

 The specimen is very typical both as to size and colour which 

 is of a rich tawny on the upper parts of the body, while the 

 under parts are pure white. 



Though the specimen (J") is quite fullgrown the skull 

 resembles very much those of Mus suriferleonis, Rob & Kloss. 

 The type of this last-mentioned subspecies was collected at 

 Changi at the north-east corner of the Singapore Island, and 

 is separated chiefly on account of its considerably smaller 

 size. The type locality for Mus surifer Miller is Träng in 

 Lower Siarn and therefore it seems more credible that the 

 specimen I collected in Eastern Siarn has to be referred to 

 the typical form. In its general appearance it is much like 

 Mus jerdoni Miller and Mus pellax Miller, but of larger 

 size. The fur is thickly spiny, and the taii is bicolour with 

 the exception of the tip which is yellowish white. 



For comparison I also give some measurements of a skull 

 of a typical Mus surifer from Träng together with the same 

 measurements of a Mus surifer leonis from Changi. 



Mus surifer 

 ö\ Träng 



Length from condylus to gnathion 39,5 mm. 



Basicranial leugth 3 6, o » 



Greatest zygomatic breadth ... 18,8 » 



Leugth of nasals 17,7 » 



Greatest breadth of nasals ... 5,5 » 



Breadth between meatus auditorius — 



Least interorbital breadth ... 7,5 » 



Length of maxillary tooth-row . . 7,0 » 



» » diastema 12,7 » 



Greatest width of brain-case . . 17, o » 

 Length from inferior margin of 

 foramen magnun to tip of pre- 



maxillary 36,5 » 



Palatilar length 18,5 » 



Length of palatilar foramina . . 7, o > 



Breadth of combined foramina . . 4, i » 



Arkiv för zoologi. Band 8. N:o 23. 



