160 



iM»)c"i;i:i)[XGs OF thk national M^sE^^r 



VOL. 85 



III Mi the protocoiiicl and nietacoiiid are ecjiial in size Avhile tlie 

 paraconid is reduced. The heel, which has a rounded posterior 

 margin, is occupied by the equally' developed entoconid and hy- 

 pocouid, which are connected by a straight ridge. A ver}- obscure 

 ridge runs across the heel portion of the tooth from the hyi)oconid 

 toward the nietaconid. This ridge is less pronoiuiced in Mo llian in 

 Ml. A small, poorly developed tubercle is present on the postero- 

 external side of the protoconid. Also, a crescent-shaped rim anterior 

 to the paraconid and protoconid is present only on the outer portion 

 of the tooth. The anteroposterior diameter of Mo is 9 mm. The 

 greatest transverse diameter of the heel is 5 mm. The greatest height 

 of the tooth, including root, is 13 mm. 



a 



Kkjukb 68. — Tomarrtus mariilaiidicn, new species, left lower molars, type specimen 

 (U. S. N. M. no. 1.">5(U) ; <i. M,, lateral view: h. IM2. lateral view; c. M,, occlusal view; 

 d. Mo, occlusal view. X 2. Calvert Miocene, Maryland. 



The two molars show very little wear, indicating that the animal 

 was in the pi'ime of life. The enamel on both is in perfect condition 

 except for small cracks. In M, the dentine can be seen at the 

 anterior end. 



Comparison. — The two molars of Tomarctus marylandica are 

 closely comi)aral)l(' to those in Tephrocyon heUoggi described by 

 Merriam ^ in 1911. The type of T, kclloggi was collected from the 

 Viigin Valley beds (middle Miocene) in Humboldt County, Nev., 

 and consists of ''a lowei- jaw with dentition." The present find and 



1 Merriam, J. C. Iiiiv. Califoiiiia I'nl)l. r.ull. I>ept. «;eol., vol. C, pj). 2:>.5-238, figs. 5, «, 

 pl. 32, inii. 



