1898.] Wort man, Extinct Camelidie of North America. 1 25 



Fig 20. Top and under view of skull oi Procainelus gracilis, after Cope. 



dency to disappear. This, it may be said, constitutes a decided 

 advance in the direction of the next genus, Pliauchenia, in which 

 this tooth is permanently ajjsent. I give herewith some compara- 

 tive measurements of the three known species in order that the 

 differences in size may be more readily understood : 



