188 PROCEEDINGS OF THE ACADEMY OF [1896. 



Phila. Col. by S. N. Rhoads on summit of Roau Mountain (6,370 

 ft.), Mitchell Co., N. Carolina, June 19, 1895. 



Description. — Size smaller than P. leucopus, with much longer 

 tail and darker coloration. 



Colors, above, blackish-brown or cinnamon with a broad, strongly 

 defined, black, vertebral stripe from middle crown to base of tail. 

 Sides of nose and a wide space around eyes, sooty. Ears dusky. 

 Hair of underparts sooty at base, scarce concealed on parts of legs, 

 throat and belly by the pure white tips. Tail sooty-brown above, 

 "white beneath, quite thickly clothed with long hairs which lengthen 

 into a pronounced pencil at tip. Skull smaller than in leucopus, 

 otherwise very similar. 



Measurements (of type in millimeters). — Total length, 170 ; tail 

 vertebrse, 87 ; hind foot, 20.5. Skull : total length, 23.8 ; basilar, 

 length, 18 ; zygomatic expansion, 13 ; interorbital constriction, 4 ; 

 length of nasals, 9.6 : length of mandible, 12.3 ; breadth of mandi- 

 ble, 6. Average measurements of four adults from the same local- 

 ity : total length, 167 ; tail vertebrre, 86 ; hind foot, 21.5. 



The Cloudland Deer Mouse seems to be exclusively a dweller of 

 the balsam or spruce belt which crowns the summit of Roan Moun- 

 tain, and is undoubtedly found on all the summits of the southern 

 Alleghenies, which rise above an altitude of 5,000 feet. That itin- 

 tergrades with leucopus of the lowlands, a total lack of specimens 

 from intermediate localities prevents me from determining. 



In a superficial comparison of nuhiterroe. with typical leucoptcs, 

 the smaller size, sooty color and very long tail immediately suggest 

 a specific diflTerence, but the cranial features of the two do not sup- 

 port such a conclusion. In all respects, except coloration and size, 

 the Roan Mountain animal is an interesting counterpart of the Per- 

 omyscus leucopus canadensis, so fully described by Mr. G.S. Miller, Jr.' 

 The diflerentiation of these two forms from leucopus has been on 

 very similar lines, owing to the similarity of the climatic conditions 

 affecting them. Their dissimilarity, on the other hand, is exactly 

 correlated with the difference in the humidity and mean temperature 

 of the balsam forests of Canada and those of the Great Smoky 

 Mountains. 



Specimens— Roan Mountain (5,500 to 6,300 ft.), Mitchell Co., N. 

 Carolina, 6 ; Carter Co., Tenn., 2. 



^Proc. Biol. Soc, Wash., Vol. VIII, 1893, pp. 55-70. 



