180 
Proceedings^ of the Biological Societi/ of ]Fashington. 
low, truncate. Incijior.s large; canines and niular.s rather small for size 
of skull. Skull of adult male unknown. 
Ursus imperator sj). nov. 
Tt/pc trom Yellowsfoiu' National I’ark, Wyoming. No. l7(iL'l)7 cJ* old, 
I . S. Nat. .Mils. ( !)ied in National Zoological Park. ) 
Cranial characters .large (slightly larger than ahsaroktts) ■, skull 
of old male (the type) massive, moderately arched, strongly dished, with 
exceedingly short frontal shield, long and high sagittal cre.st, and’ long 
peg-like outstanding postorhital processes. Muzzle short, narrow for so 
large a skull, somewhat compressed helow' nasals; nasals nearly hoi'i- 
zontal; frontal shield rising strongly just in front of orbits, fiattish, 
shallowly silicate medially, ending in short obtuse point about .'lO mm. 
behind plain' ol postorbitals; postorbitals long, peg-like, horizontally 
outstanding; hraincase long; lachrymal duct opening on orbital rim; 
zygomata moderately outstanding and outbowed, the squamosal base 
bioadly expanded; squamosal shelves liroad, arched over meatus; jialate 
moderate; postiialatal shelf long; occifiito-sphenoid 91 mm.; mastoids 
short; lower jaw large, long, and ma.sMve, with high vertical coronoid 
blade. Teeth large. 
^ Old male rniperalor {the tiipe) compared irlth old male absarokns (No. 
-89;j I . S. Nat. Mus.); Size larger; frontal shield broader; postorbital 
processes longer and more widely outstanding; rostrum higber and more 
horizontal (in absarokas lower anteriorly and more sloping); sagittal 
crest longer, its free edge nearly straight instead of arched ;'’s(piamosal 
root ot zygoma very much more expanded vertically; palate much longer; 
lower jaw longer and more massive. 
Compared ivilh old male stikeenemus (No. 171049): Much larger and 
morenias.dve; frontal shield Hatter; sipianiosal liase of zygoma vepy much 
more broadly expanded ; palati* and postpalatal sbelf much longer'; lower 
jaw' much longer; coronoid blade much higher and more vertical. 
()l.l female imperator (No. 177(;(iO T. S. Nat. .Mus., Ifiological Survey 
( oil., collected near hake Iloti*i, Yellowstone National Park, .Julj' ’JO, 
1911. I)y Dr. P. S. Kellogg): Size large; zygomata moderately spreading’, 
only slightly outbowed; braincase ratber short, broadly rounded, witbout 
tendency to “ keeling ” ; frontal sbicid rather broad, llattisb, sligbtly 
convex laterally, sligbtly silicate medially, its sub-lyrate point’reacbing 
fronto-paru'tal suture; postorbital i)roce.sses ratber large and short, oiit- 
shinding, liliint or subtriangular, deciirved ; fronto-nasal region somewhat 
dislied; rostrum broad, high, and rather short; lachrymal duct cutting 
orbital run ; squamosal arm of zygoma moderah'ly exjianded, the anterior 
root .strongly swollen under front of orbit; .sagittal cre.st moderate, nearly 
covering parietal; occiput obliipiely truncate; inion moderate; palate 
broad; occipito-sphenoid about SO mm.; under jaw’ large and massive, 
leetli large, much as in female absarokas but upper molars broader- 
canines and molars much larger than in female Ursus shoshone. 
Old female imperator (No. 777000} compared vrith old female stikeenensis 
{^o. ISOOSI): Skulls surprisingly alike in size, geiH'ral form, and propor- 
