208 ' MILLER 



pale straw-yellow, brighter on chest, duller and more nearly ci'eam 

 color posteriorly. The yellow of legs is continuous with dirty white 

 of upper surface of feet. Metapodials heavily shaded with brown. 

 Tail dull light brown, indistinctly paler beneath and throughout ter- 

 minal third. 



Skull and teeth. — The skull differs from that oi Jlfus vociferans 

 and resembles that of M. sabanus in the elevation of the region about 

 posterior extremity of nasals. The character is one that is almost im- 

 possible to describe, but which is readily appreciated on comparison 

 of specimens. Teeth as in the related species. 



Measuroiients. — External measurements of type : total length 

 565; head and body 241 ; tail vertebra 324; hind foot 47 (43.6) ; ear 

 from meatus 22; ear from crown 20; width of ear iS. Four speci- 

 mens from Pulo Siantan average : total length 546 (509-5S4) ; head 

 and body 235 (222-248); tail vertebrte 311 (29S-336) ; hind foot 

 46.4 (45-47); hind foot without claws 44. 1 (43-45). Three speci- 

 mens from Pulo Jimaja average : total length 551 (547-559); head 

 and body 233 (229-241) ; tail vertebrae 31S ; hind foot 45.5 (45-46) ; 

 hind foot without claws 44 (43-45). 



Cranial measurements of type : greatest length 57 ; basal length 48 ; 

 basilar length 45; palatal length 25.4; least width of palate between 

 anterior molars 5; diastema 15.6; length of incisive foramen 8; com- 

 bined breadth of incisive foramina 4; length of nasals 11.8; com- 

 bined breadth of nasals 6 ; zygomatic breadth 25 ; interorbital breadth 

 9.6; mastoid breadth 19; breadth of braincase over roots of zygomata 

 20; depth of braincase at front of basioccipital 13.S; frontopalatal depth 

 at posterior extremity of nasals 14 ; least depth of rostrum immediately 

 behind incisors 10; maxillary toothrow (alveoli) 10; width of first 

 upper molar 3; mandible 32.4; mandibular toothrow (alveoli) 9.6. 



Specimens cxa?nined. — Seven; four from Pulo Siantan and three 

 from Pulo Jimaja. 



Remarks. — Its dark color immediately distinguishes this rat from 

 JMus vociferatis and AI. sabanus. The seven specimens are remark- 

 ably constant in all their characters, both external and cranial. None 

 of them show a tendency to become markedly paler and yellower 

 across the shoulders so conspicuous in Mus vociferans. Dr. Abbott 

 notes that the animal is quite as noisy as its mainland representative. 



?MUS VOCIFERANS Miller. 

 A single much al)radcd specimen ( 9 No. 101756) taken on Tionian 

 Island, October 3, 1S99, is probably referable to this species. Its 



