Miller. — Seven Keir liafs coJlected In Slam. 147 



Mus pellax sp. nov. 



Tjipe -aClxxW, female (skin and skull) No. 80,755 United Stales National 

 Museum, collected in the mountains of Trong-, Lower Siam, at an alti- 

 tude of about 1000 ft., February 5, 1899. 



Charaetera. — Closely related to Mmjerdoni Blyth from Mount Mooleyit, 

 Burmah, but with larger skull and teeth, much shorter incisive foramina 

 and relatively smaller audital bulhe. Namls extending conspicuously be- 

 hind nasal branches of premaxillaries. White of inner side of thigh con- 

 tinued along lower leg to join that of foot, as in Mus jerdoni. 



Fur. — The fur is as in Musjerdoni and M. erevwruenter. 



Color. — Back and sides clay color tinged with ochraceous, particularly 

 on shoulders and flanks, and everywhere darkened by mixture of Van- 

 dyke brown, the latter in excess over middle of back, nearly disappear- 

 ing on sides. Underparts white, sharply defined, this color extending 

 down inner side of legs and covering dorsal surface of feet. Muzzle 

 hair brown. Face and crown like back. An ill defined brown eyering. 

 Between ears there is a conspicuous elongate white spot, possibly due to 

 albinism. Ears dark brow^n. Tail bicolor. but not sharply so, light brown 

 above, whitish below, the colors becoming indefinite near tip. 



Tail. — The tail is indistinctly annulated; ten rings tothe centimeter at 

 middle. The rings are not sharply defined. Each is divided into seg- 

 ments distinctly broader than long. From beneath the free edges of the 

 rings grows numerous hairs whose length about equals width of two 

 rings. These hairs are not definitely arranged, and from one to four 

 spring from each section. At tip the rings become very irregular, but 

 the hairs, contrary to the general rule, are reduced in length. 



iSkulL — Though noticeably larger than that of Mus jerdoni the skull of 

 Mus pellax does not dift'er from it in general form. The audital bulhe 

 are a shade smaller than in Mus jerdoni, therefore relatively of much less 

 size. Incisive foramina short and broad, the outer margins converging 

 anteriorly. Nasals extending nearly ;5 mm. behind nasal branches of 

 premaxillaries. At anterior extremity each nasal is emarginated on 

 outer side so that the two together form a narrow median point. Other- 

 wise the skull agrees with that of Mu.s jerdoni. 



Teeth. — The teeth are much broader than those of Mus jerdoni. Enam- 

 el pattern as in M. jerdoni ?in(\ M. derunianux except in the presence of a 

 minute supplemental tubercle between first and second tubercles on in- 

 ner side of second upper molar. Though present and perfectly symmet- 

 rical in the tooth of each side it is probably not a normal character. 



Measurements. — External measurements of type: total length, 317; 

 head and body, 152; tail vertebra\ 1(55; hind foot, 35 (33); ear from 

 meatus, 21; ear from crown, IG; width of ear, 17. 



Cranial measurements of type: greatest length, 41; basal length, 34; 

 basilar length, 31; palatal length, 17; least width of palate between an- 

 terior molars, 4; diastema, 11.5; length of incisive foramen, (5; combined 

 breadth of incisive foramina, 3; length of nasals, 10; combined breadth 

 of nasals, 4.8; zygomatic breadth, 18; inteporbital breadth, 6.4; mastoid 



