Miller. Seven New Ruts collected in Slum. 147 



Mus pellax sp. nov. 



Type adult female (skin and skull) No. 86,755 United States National 

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

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



Characters. Closely related to Musjerdoni Blyth from Mount Mooleyit, 

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

 and relatively smaller audital bullae. Nasals extending consjncuously be 

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

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



Fur. The fur is as in Musjerdoni and M. cremoriT enter. 



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 denned, this color extending 

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

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

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

 albinism. Ears dark brown. 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 to the 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. 



Skull. Though noticeably larger than that of Musjerdoni the skull of 

 Mus pellax does not differ from it in general form. The audital bulla? 

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

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

 anteriorly. Nasals extending nearly 3 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 Musjerdoni. 



Teeth. The teeth are much broader than those of Musjerdoni. Enam 

 el pattern as in M. jerdoni and M. decumanus 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, 817; 

 head and body, 152; tail vertebrae, 165; hind foot, 35 (33); ear from 

 meatus, 21; ear from crown, 16; 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, 6; combined 

 breadth of incisive foramina, 3; length of nasals, 16; combined breadth 

 of nasals, 4.8; zygomatic breadth, 18; interorbital breadth, 6,4; mastoid. 



