238 The American Naturalist. [March, 



faces pure white. Half grown young in July and August like adult, 

 but darker, owing to greater abundance of colored hairs and the leaden 

 under fur. Appearances of young and old at a distance at all seasons, 



Winter pelage, pure white throughout, except the tips of ears, which 

 are black. 



Skull with rostral portion anterior to pnU, relatively much longer 

 and more attenuate, owing to the outward prolongation of the pre- 

 maxiiraries and the small calibre of incisors. Upper and lower incis- 

 ors very long, produced and slender, their transverse diameter being 

 less than the longitudinal. Upper incisors describe the arc of a circle 

 whose radius is one-fifth ( T 2 «&) the basilar length of the skull. The 

 chord of their exposed arcs (with cranium, minus mandibles, resting 

 on a plane horizontal surface) forms an angle of 45° to the horizontal 

 plane. Face of upper incisors multistriate, the normal sulcus peculiar 

 to all other members of the genus being so filled with dentine in adult 

 grcenlandiom as to obliterate the depression, presenting an even, 

 rounded, enameled contour marked with three minute striae. 



Roots of upper incisors based on the maxillaries and reaching back 

 nearly half way from inferior maxillo-premaxillary sutures to pm. 1 . 

 Roots of lower incisors extending to the base of pm. 2. 



Measurements (of type taken from dry mounted skin, relaxed) : ear, 

 from crown, 100 millimeters ; hind foot, 145 ; tail vertebrae (dry), 50 ? 



Skull : total length, 100 ; basilar length, 84.5 ; greatest breadth, 50 ; 

 anterior frontal constriction, 22.5 ; length of nasals (longest diagonal), 

 41 ; greatest breadth of nasals, 20.5 ; alveolar breadth of upper incis- 

 ors, 8.5 ; greatest length of mandible, 76 ; greatest width of mandible, 

 48. 



Five skins, seven skulls, and one skeleton, all from North Green- 

 land, comprise the Academy series of Greenland Hares, and all con- 

 firm the peculiar characters of this species as above given. I regret 

 that more complete body measurements are not available. Average 

 adult measurements of ear and hind foot are 100 millimeters for the 

 former and 145 for the latter. The total length of an adult skeleton 

 (ligamentous) is 519 millimeters, measured as in the flesh, from tip of 

 nose to end of tail vertebrae. 



It is possible that Spitzbergen and Iceland Hares are of the same 

 type as those of Greenland. None of these have come into my hands. 

 The Bavarian, Swiss, Scottish, Irish and Siberian representatives of 

 timidus are also likely to prove separable, at least into definable races, 

 already named. From what is known of Linnaeus at the time of writ- 



