NEW PALEOCENE MAMMALS SIMPSOK 



235 



CHRIACUS PUGNAX.3I new species 



Type. — U.S.N.M. no. 13782, right lower jaw with Mi_2 and alveoli. 

 Collected by A. C. Silberhng and G. G. Simpson, 1932. 



Horizon and locality. — Locality 78, Fort Union, probably Middle 

 Paleocene (older than Gidley Quarry), Crazy Mountain Field, Mont. 



Diagnosis. — Much larger than C. pusillus, about the size of C. pel- 

 videns, but molars markedly wider, trigonids less elevated, talonid of 

 Ml notably wider than trigonid. Mi length 7 mm, width trigonid 

 4.9 mm, width talonid 5.9 mm. 



METACHRIACUS,32 new genus 



Type. — Metachriacus punitor, new species. 



Distribution. — Middle Paleocene, Fort Union, Mont. 



Diagnosis. — Premolars like Chriacus. Molar trigonids less ele- 

 vated, paraconids reduced but near metaconids, trigonid basin with 

 crenulated anterior margin, accessory cuspules also tending to develop 

 elsewhere, especially on notched mctaconid-entoconid crest. Molars 

 wide and heavy, especially Ma. 



METACHRIACUS PUNITOR,'' new species 



Type.— U.S. 'N.M. no. 9288, left lower jaw with M1-3. Collected 

 by A. C. Silberhng. 



Paratype. — U.S.N.M. no. 9286, right lower jaw with P3-M3 

 (Ml and M3 broken). Collected by A. C. Silberhng. 



Horizon and locality. — Gidley Quarry, Fort Union, Middle Paleo- 

 cene horizon. Crazy Mountain Field, Mont. 



Diagnosis. — Heel of P4 squarely truncated, inner side nearly 

 basined, with two cuspules. Molars relatively weak, crenulation 

 moderate. Measurements of type in millimeters: 



METACHRIACUS PROVOCATOR,3< new species 



Type.—U.S.'N.M. no. 9278, left lower jaw with P4-M3. Collected 

 by Dr. J. W. Gidley. 



Horizon and locality. — Locahty 51 (probably referable specimen 

 from locahty no. 24, near same level, both below Gidley Quarry), 

 Fort Union, Middle Paleocene horizon. Crazy Mountain Field, Mont. 



Diagnosis. — Heel of P4 more pointed, only one distinct cusp. 

 Molars very broad and heavy, crenulations pronounced. Measure- 

 ments of type in millimeters: 



•1 Pugnax, combative. " Punitor, avenger. 



»" UtTa, prefix of change of condition, etc. +ChTiacus. " Provocator, one who challenges to combat. 



