1897.] NATURAL SCIENCES OF PHILADELPHIA. 491 



Syn. Bison crassicornis Richardson, Zool. Voy. Herald, 1854, pp. 

 42, 43, PI. XIII, figs. 1 and 2 (including solely the references to 

 large $ horn-core " No. 91 "). 



General characters. — Size intermediate between B. antiquus and 

 B. alleni; frontal breadth equalling that of B. latifrons, the occi- 

 pital development much weaker. Horn-cores strongly curved up- 

 ward and forward, their tips reaching behind the plane of the occi- 

 put ; greatly flattened and smooth superiorly, broadly rounded and 

 deeply furrowed interiorly, showing a rounded hemispheric outline 

 in median cross-section as contrasted with type of crampianus (= 

 alleni). Frontal and occipital characters as in B. bison and its 

 other extinct allies, when contrasted with Old World forms. Ratio 

 of length of single horn-core to breadth of frontals between horn- 

 cores much smaller than in type of crampianus 9 (=alleni) and lati- 

 frons. Ratio of greatest median diameter of horn-core to the least 

 median diameter of same, much less than in any known American 

 species of bison. For more detailed comparative characters con- 

 sult the preceding pages of this paper. 



Measurements.'— Greatest extent of horn-cores, measured between 

 tips, 1,130 mm. ; chord of arc of left horn-core from tip to superior 

 base, 405 mm. ; shortest frontal width between basilar processes of 

 horn-cores, 465 mm. ; greatest interorbital width, 400 mm. ; length 

 from basal suture of nasals to posterior edge of occipital crest, meas- 

 ured along mesial frontal profile, 333 mm. ; greatest mastoid 

 breadth, 308 mm. ; vertical height of occiput, from lower border of 

 foramen magnum to highest point of occipital crest, 174 mm. ; great- 

 est width between the outer edges of the lateral wings of the con- 

 dyles, 162 mm.; girth of frontal shoulder of left horn-core, meas- 

 ured 20 mm. from basal border of core, 349 mm. ; greatest girth 

 of left horn-core, measured along basal border, 410 mm. ; girth of 

 left horn-core at a point 200 mm. from its inferior basal border, 

 241 mm.; greatest diameter of core at same point, 86 mm.; least 

 diameter of core at same point, 66 mm.; length of left horn-core meas- 

 ured along superior arc (adding 15 mm. for portion of tip worn ofl), 

 497 mm.; the same measured along inferior arc of same, 526 mm. 



Habitat and Geologic Position. — Northern Alaska (and British 

 America?) from Kotzebue Sound northward ; living in early Plis- 

 tocene time, anterior to but perhaps overlapping the existence of the 



9 Judging by the dimensions of the antorbital- section of the type of cram- 

 pianus, its cranium was about the same size as those of alaskensis and latlfrons. 



