PETERSON: A REVISION OF THE ENTELODONTIDA® 49 
fragments of skull and lower jaws (No. 2011, Carnegie Museum Cat. Foss. Vert.), 
was collected in the Oreodon beds near Dickinson in the Little Bad-lands of North 
Dakota by Earl Douglass. This has the entoconid of Mz well represented, the 
anterior tubercles of the lower molars very high, as in A. coarctatwm, the premolars 1 
rather small, but Pz separated from Pz by a diastema as in A. mortoni. The upper 
molars are relatively longer and narrower than those in the typical specimens of A. 
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Fia. 6. Palatal View of Cranium of Archzotherium mortoni Leidy. 4 nat. size. (Carn. Mus. Cat. Vert. Foss. No. 
1900.) The oblong area in front of the condyle represents the broken tympanic bull. 
mortoni. This would seem to indicate that there is a considerable range of indi- 
vidual variation in the species A. mortoni. 
Archeotherium mortoni subsp. clavum (Marsh). 
Type: Skull. 
Horizon: Lower Oligocene (‘Titanotherium beds). 
Locality: Bad-lands of South Dakota. 
Locality of Type: In Collection of Yale Museum, No. 2035. 
The type of this subspecies is the skull of an animal the size of Archiotherium 
mortom, and the characters which Professor Marsh has given do not clearly distin- 
Suish it from the latter species. Marsh states that the skull agrees in many respects 
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