1894.] NATURAL SCIENCES OF PHILADELPHIA. 259 



Five specimens of this mouse, two adult and three somewhat 

 immature, were received by me through courtesy of Mr. James 

 Fletcher, of the Canadian Experimental Farm, at Ottawa. Mr. 

 Fletcher received them from Mr. Keen, who resides on the Queen 

 Charlotte Islands. I take pleasure in naming the animal after its 

 discoverer, and trust it may be some incentive to more extended 

 researches in this interesting and imperfectly known department of 

 northwest zoology. 



The specimens were sent in carbolized spirits. The purity of the 

 white after drying them out, shows their colors not to have altered, 

 and indicates that a series of well-preserved skins would show keeni 

 to be the darkest colored Sitomijs yet brought to notice, a condition 

 of affairs which our knowledge of their humid, insular environment 

 would lead us to expect. 



5. Sitomys macrorhinus sp. nov. Type, No. 1,381, ad. 9, Coll. S. N. Rhoads. 

 Skueiiii Kiver, British Coltiiubia, July 20th, 1893. Col. by Eev. J. H. Keen 



Description. — Size much larger than S. americanus. Tail con- 

 siderably longer than head and body, feet large, ears medium. 

 Colors much as in keeni (1. c. ), but grayer and lighter hued above, 

 without the sooty cast of Iceeni. The tail is more coarsely hairy and 

 the hairs longer than in keeni, forming a distinct pencil not seen in 

 that species. Skull, viewed above, of the same triangular type as 

 keeni, due to its antorbital constriction, but departing widely from 

 any other Sitomi/s I have examined, in the great relative length of 

 the rostrum (or that portion of the skull anterior to the interorbital 

 constriction ) to the total length of the skull. In all others examined 

 this dimension is less than that of the post interorbital region, taking 

 for the central point of measurement the narrowest constriction point 

 of the froutals. In macrorhinus this condition is reversed. The 

 relative length of the nasal bones in this species is not great, but the 

 slenderness of the rostrum and the anterior compression of the jugal 

 arch increases their apparent length and the relative prominence of 

 this portion of the cranium. These differences, coupled with the 

 large size of the skull, strongly define macrorhinus from any of its 

 geographic allies. 



Measurements. — Total length, 210 mm; tail vertebrae, 112; hind 

 foot, 25; ear from crown, 15; tail pencil, 6. Skull — Total length, 

 29; basilar length, 22-4; zygomatic width, 14-5; length of nasals. 



