Vol. 5] 



Merriam. — John Day Carnivora. 



31 



Distinctive Characters. — Cranium with well-developed brain 

 case, and large thin-walled auditory bullae. Two pair of post- 

 parietal foramina present. Mandible short, uncommonly heavy 

 anteriorly. Dentition f ), T , -3, 3. Premolars heavy, P2 with- 

 out basal tubercles, P 3 and P 4 with anterior and posterior basal 

 tubercles and posterior cusp. M 1 with well-developed shear and 

 somewhat reduced metaconid. The somewhat elevated hypoconid 

 occupies about half of the broad heel of M 15 entoconid low. M 2 

 without prominent paraconid, M 3 in general like M 2 . 



Skull. — The fragment of the cranium shows a brain case and 

 posterior cranial crests of moderate proportions. The crests are 

 about as prominent as in Mesocyon coryphaeus. The otic bulla 

 present is thin-walled and large. It is almost entirely separated 

 from the postglenoid process. The paroccipital process is slen- 

 der. There are two postparietal foramina, of which the larger, 

 anterior one is situated a little more than half way up the side 

 of the brain case and in front of the lambdoidal crest. The 

 smaller, posterior foramen is located considerably higher up and 

 on the base of the lambdoidal crest, much as in the postparietal 

 foramina of Enhydrocyon. The postglenoid foramen is situated 

 very close to the median border of the postglenoid process. The 

 situation of the condylar foramen is much as in Canis. 



The mandible is short and the posterior end of the dental 

 series is considerably elevated. The anterior portion of the jaw 

 is more than ordinarily heavy. The inferior border is only 

 slightly convex. The massateric fossa reaches forward to a point 

 below the posterior end of M 2 . 



Dentition. — The dentition, so far as known, is 3 ('?), T , 

 Viewed from above, the dental series is seen to curve toward the 

 median line rather sharply in front of the last premolar as in 

 other short- jawed forms. The enamel of all the teeth is more or 

 less rugose. 



Only one incisor, I 3 ( ?), is present in the jaw. It is a rela- 

 tively small tooth with a small lateral cusp which is only a little 

 lower than the principal cusp. The symphyseal region is uncom- 

 monly narrow and the space between the outer incisor and the 

 symphysis is occupied by an antero-posteriorly elongated pit 

 which does not include more than half of the area. A very small 



