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EXPLANATION OF PLATES 



Plate i 



Mytonomeryx scotti, new genus and species : Dorsal, lateral, and ventral views 

 of skull and lateral view of left ramus mandible (U.S.N. M. No. 20401), 

 type specimen. Natural size. Myton pocket, Uinta Basin, Utah. 



Plate 2 



Above, Pentacemylus progressus Peterson: Left maxilla (U.S.N.M. No. 20435), 



occlusal view of teeth. Approximately three times natural size. Myton 



pocket, Uinta Basin, Utah. 

 Below, Mytonomeryx scotti, new genus and species: Skull (U.S.N.M. No. 



20401), type specimen, occlusal view of teeth. Approximately three times 



natural size. Myton pocket, Uinta Basin, Utah. 



Plate 3 



Fig. I. Mytonomeryx scotti, new genus and species: Left ramus of mandible 

 (U.S.N.M. No. 20401), type specimen, occlusal view of teeth. Approxi- 

 mately one and one-half times natural size. Myton pocket, Uinta Basin, 

 Utah. 



Figs. 2, 3. Pentacemylus progressus Peterson: 2, Left ramus of mandible 

 (U.S.N.M. No. 20437), occlusal view of teeth; 3, left ramus of mandible 

 (U.S.N.M. No. 20438), lateral view. Approximately one and one-half times 

 natural size. Myton pocket, Uinta Basin, Utah. 



Fig. 4. Hylomeryx quadricuspis (Peterson) : Right ramus of mandible (CM. 

 No. 2346), type specimen, occlusal and lateral views. Approximately three 

 lateral view. Natural size. Leland Bench draw, Uinta Basin, Utah. 



