EXPLANATION OF PLATE I. 



Fig. 1. Oreodon supeebus: 



A side view of a skull, witli the base of tbe cranium iuvested in tlie matrix. Specimen ob- 

 tained by Rev. Thomas Condon on John Day's River, Oregon. One-half the natural size. 



Figs. 2,3. MEGACfiROPS COI.ORADENSIS : 



Fig. 2. Upper view of the nasal extremity of the face with a pair of horn-cores. Oue-half 



the natural size. 

 Fig. 3. Front view of the same specimen 



