PLATE I. 



Fig. Page 



1. Arsinoitherium zitteli, Beadnell; skull, left lateral view; the ends of the 

 horns have been restored : one-third nat. size. Fluvio-marine beds 

 (Upper Eocene). [M. 8463.] 2 



ao.f., antorbital foramen. 

 h.v., h.v.' , impressions of blood-vessels. 

 c, alveolus of canine. 

 e.a.m., external auditory meatus. 

 exo., exoccipital. 

 /./(., frontal horn. 

 f.l.a., foramen lacerum anterius. 



fr., frontal. 

 i. 1-3, incisors or their alveoli. 

 ju., jugal. 

 I., lachrymal. 

 m. 1-3, molars. 

 mes., prenasal bar. 

 mx., maxilla. 

 ua., nasal. 



nar., external nares. 

 n.Ji., nasal horn. 

 on.f., orbito-nasal foramen. 

 pa., parietal. 

 pgl., postglenoid process. 



pi., palatine. 

 pm. 1-4, premolars or their alveoli. 

 pmx., premaxilla. 

 p.p., paroceipital process. 



pt, pterygoid. 

 piy., post-tympanic process. 



sq., squamosal. 

 st.r., supratemporal ridge. 



II., optic foramen. 



