372 PROCEEDINGS OF THE ACADEMY OF [1896. 



ing behind bases of nasals. Supraorbital processes as in bangsi. 

 Posterior interorbital constriction narrow, its relative width to al- 

 veolar length of upper molar series as in grcenlandicus. Upper an- 

 terior incisors rooted as in arcticus, their roots not forming decided 

 maxillar convexities, owing to the great relative width of rostrum. 

 Form and position of incisors as in arcticus, but heavier. Molars 

 much heavier. Incisive foramina as in arcticus. Palatal bridge as 

 in grcenlandicus. Palatine foramina as in grcenlandicus. 



Measurements. — Average of three adults: bind foot, 176 milli- 

 meters; ear, from crown, 96. Skull: total length 103.5 ; greatest 

 breadth 54 ^ greatest (diagonal) length of nasal 42.5 ; greatest 

 breadth of nasals 23; width, at tip, of upper incisors 66; alveolar 

 width of upper incisors 9.8 ; alveolar length of upper molar series 

 20 ; greatest length of mandible 80 ; greatest width of mandible 51. 



General remarks. — The Polar Hare of West Alaska, as will be 

 seen by its measurements, represents the maximum development of 

 the Arctic group in America. Added to great size we have in 

 tschuktschorum several cranial and external characters which sepa- 

 rate it from arcticus and its eastern subspecies so plainly that there 

 is little doubt of their specific value. Among these we may note 

 an approach in color to timidus of Sweden, but the uniformly broad 

 flattened nasals, the great relative width of skull and large calibre 

 of the dental armature and the anvil-shaped, upraised supraorbital 

 processes induce me to specifically distinguish it. A skull from 

 Plover Bay (Smith. Inst., No. 7,180) should be classed strictly as 

 tschuktschorum. Reference to the table of measurements shows 

 its dimensions to be of the largest. The relative zygomatic width 

 is narrower, but in all other respects the Siberian skull is typical of 

 the Alaskan as contrasted with the Scandinavian and Baffin Land 

 animals. The researches of Radde'" and Middendorff"" show that 

 the Polar Hares of east Siberia do not specifically diflfer from the 

 European species either in color or in cranial characters, the latter 

 mentioning the occurrence of this species in the Stanovoi Range 

 which extends into the Tschuktschee country. Four skulls from 

 Karatchatka, in the collection of the Smithsonian Institution, show 

 beyond question that the small timidus type of Polar Hare inhabit- 

 ing that region is very different from the hare which frequents the 



'"Reisen im Ost-Sibirien, I, 1862, pp. 207-211. 

 ''^ Sibirische Reise, II, 1853, p. 115. 



