PREFATORY NOTE 



Procamdiis major (Leidy) appears to be a valid species, while the specific 

 identity of ProcameliLS medhis and P. minor is not yet proven. The same may 

 perhaps be said of Mastodon floridamis, but until other specimens of Mastodon 

 scrridcns can be secured Mastodon floridanns should undoubtedly be con- 

 sidered as distinct. Hippotlicrium princeps, in the opinion of the writer, rests 

 on an abnormal tooth of Eqinis major. 



With the exception of the paragraphs on the tusks the most important 

 part of this memoir, that relating to Mastodon floridan?is, was written by Dr. 

 Leidy, as was also most of the description of the three species of Procainehis. 

 The portions treating of Rhinoceros and Hippothcrinm were prepared by the 

 writer, whose initials are appended to these and to other parts for which he is 

 responsible. 



In view of the numerous and accurate illustrations prepared by Miss 

 Sinclair, which will furnish important and much-needed means of comparison 

 with other material, the descriptions have purposely been made brief 



I am indebted to Professor Cope for the privilege of examining the types 

 of various species in his possession, and a considerable number of specimens 

 oi Procainehis collected by the Geological Survey of Texas. 



Frederic A. Lucas. 



Washington, D.C, 

 June 30, It 



