1894.] NATURAL SCIENCES OF PHILADELPHIA. 421 



A NEW JUMPING MOTJSE FEOM THE PACIFIC SLOPE. 

 BY SAMUEL N. RHOADS. 



Zapus trinotatus sp. nov. Type, ad $ , No. 360, Coll. of S. N. Ehoads. Lulu 

 Island (mouth of Frazer River), British Columbia, May 31st, 1892. Col. 

 by S. X. E. 



Description. — Size large, equalling Zapiis princeps from Colorado, 

 hut with a shorter foot. Colors above as in princeps, but darker, 

 the yellowish- gray suffusion on back and sides of that species being 

 replaced in trinotatus by brownish-fulvous ; the cheeks, ears, upper 

 head, circumocular region, and upper surface of tail much blacker. 

 The upper surface of wrist is black with fulvous anterior edging 

 reaching to foot. Lateral stripe separating upper and lower body 

 colors, dark fulvous, narrow, and reaching from hams to and around 

 front of fore legs, and nearly meeting across throat. The throat, 

 chin, belly, vent, and lower (inner) surfaces of legs are a clear soft 

 white. In the center of lower throat and on each side of the sternum 

 is a well-defined spot of fulvous about 8 mm. long and 3 ram. wide, 

 the pectoral spots being the larger and more strongly colored. The 

 fulvous of these spots does not reach base of hairs, their roots being 

 white, as in the hairs of the fulvous lateral stripe. 



Skull differing from any described form in its great relative width 

 and depth, to length, the zygomse being more flaring, the parietals 

 more convex, the incisive foramina larger and broader posteriorly, 

 the postpalatal notch more acuminate and indenting the palatal 

 bones as far as m. 2. The upper premolar is larger than in princeps 

 or hiidsonius, its crown rising to the grinding plane of the true 

 molars and becoming functional, bearing on its inner and posterior 

 rim a crescentine loop partially enclosing a central cusp whose base 

 lies on the outer anterior angle of the crown. In princeps, its 

 nearest ally, this tooth is not functional, or rarely so, its apex falling 

 below the grinding plane, and, as in kudsonius, consisting of a 

 simple peg- like process with the folding being more or less obsolete. 

 The lower molars of trinotatus are relatively larger than iu princeps 

 or kudsonius, the posterior loop of m. 1 and the second and last loops 



