Cope.] ^ 14 [j aQt 18> 



a. Infraorbital foramen above front of P-m. iii. 

 Skull depressed, muzzle short ; paroccipital process behind 

 bulla and not separated from it by grooves ; bulla grooved 

 to apex for styloid ligament, etc. ; zygoma more robust. 



E. trigonocephaly. 

 II. Palatonareal border in line with posterior edges of maxillary bones, 

 aa. Infraorbital foramen above posterior part of third premolar. 

 Paroccipital process behind otic bulla, the internal border of 



its base opposite that of the bulla E. jacksoni. 



Paroccipital process external to the middle of the otic bulla ; 



generally larger E. major. 



The name here employed for this genus is the one first given with a 

 definition. The typical species, E. jacksoni, was widely distributed, and 

 appears under several varietal forms and sizes, some of which have re- 

 ceived names. Subsequently to the original description, Dr. Leidy added 

 to the genus a second species, which probably belongs to the genus 

 Agriochoerus. On this account Leidy inclined at one time to combine the 

 two genera, but afterwards abandoned the idea. 



Eucrotaphus trigonocephalus, sp. nov. 



This distinct form is only known to me from a single skull of an old 

 animal. In the character of its otic bulla it has resemblance to the species 

 of Agriochoerus, while the maxillary part of the skull has the posterior 

 position of a true Oreodon. 



The muzzle is rather depressed, and the premaxillary alveolar border is 

 almost transverse. The position of the canine alveolus is swollen later- 

 ally, and between it and the infraorbital foramen the side of the face is 

 slightly concave. The expansion leading to the malar bone commences as 

 the posterior slope of the concavity mentioned, and spreads laterally, without 

 interruption, beginning to project beyond the superior alveolar border at 

 the fourth superior premolar. In the E. jacksoni this is not apparent 

 anterior to the first true molar. The top of the muzzle and the front are 

 wider than in that species, and are gently concave in the transverse direc- 

 tion. The anterior temporal ridges are well defined, and concave in out- 

 line, uniting early to form a prominent sagittal crest. The malar bone is 

 a little concave below the orbit. The malar process of the maxillary pro- 

 jects downwards in an obtuse angle, opposite the penultimate superior 

 molar. In E. jacksoni the malar is convex, and the tuberosity is opposite 

 the last molar. The squamosal process is deeper than in the E. jacksoni, 

 and sends a more robust apex into the malar bone, the apex not extending 

 in front of the posterior border of the orbit. The supraoccipital crests are 

 well developed, and project beyond the vertical plane of the condyles ; 

 they continue into well marked posttemporal crests, as in the other species 

 of the genus, as well as send an obtuse ridge downwards on each side to- 

 wards the foramen magnum. The median supraoccipital plane disappears 

 downwards in a wedge-shaped apex, which causes the transverse section 



