240 An Oregon Mouse. 



AN OREGON MOUSE. 



Frederick W. True has recently described a new species of mouse 

 in the Proceedings of the U. S. National Museum (xiii, 303-4), from 

 a specimen sent by the writer to the Smithsonian Institution, to 

 which the name Phenacomys longicaudus has been given. The fol- 

 lowing description of this interesting animal is taken from Mr. 

 True's paper: 



Size moderate, about equalling that of Hesperomys leucopus. 

 Ears moderate, nearly concealed by the surrounding fur. Hind foot 

 not relatively longer than in the other species of the genus. Tail 

 long; with the hairs, equal to the body in length. 



Color above nearly uniform bright rusty brown; only the tips 

 of the hairs are of this color, the remainder being dark plumbeous. 

 Mixed with the brown-tipped hairs are numerous longer black 

 hairs. Under surfaces white, slightly tinged with rusty brown, es- 

 pecially on the abdomen. The hairs of the throat are white to the 

 base, but elsewhere they are only tipped with light color, the lower 

 portions being plumbeous. 



The tail is dusky chocolate-brown above and below. Fore feet 



brown, like the upper surface of the body; toes more or less dusky. 



Hind feet similar, but the toes more dusky. A spot on the outside 



„ of the metatarsus lighter than the rest of the foot. A portion of the 



whiskers dusky, the rest whitish. Nose dusky. 



Measurements. (Dry skin No. HVd, type).— Total length, 

 148 ,nm ; tail, with hairs, 62 mm ; hind foot, 20.2 mm ; ear from be- 

 hind, 4.6 mm . 



The skull belonging to the type is badly broken, and it is only 

 possible to give the dimensions of some of its parts. 



Measurements of the skull. — Length of the crowns of the upper 

 series of molar teeth, 5.8 mm ; lower molars, 5.7 ram ; length of nasal 

 bone, 6.6 mm ; breadth of interorbital construction, 2.8 mm . 



The molar teeth resemble those of P. intermedius, but the loz- 

 enges are narrower, and the external re-entrant folds of enamel in 

 the upper molars are directed less backwards and those of the lower 

 molars less forwards than in that species. The molars are rooted. 

 The skull is that of a youngish individual. 



Regarding the habits of this mouse, I would say that it seems 

 to be almost exclusively arboreal, having only been taken, so far as 

 I am able to learn, in the branches of the Douglas spruce. The type 

 specimen was sent me from Marshfield, Coos county, Ore., by a 

 friend, L. J. Cornelius, of Siuslaw River, who had shown me a nest 

 of this, built about 60 feet from the ground in a small clump of 



