4 DINOCEItATA. 



Other important specimens, obtained at this time, and described by the 

 author, were the types of Dinoceras lucare, Tinocems gnmde, Tinoceras 

 lacustre, and others of scarcely less interest. 



In the following season, 1873, tlie author organized another large 

 expedition, with government escort, and made a very careful examination 

 of the regions in this same basin that remained unexplored. One of the 

 specimens of special importance thus secured was the type of Dinoceras 

 laficeps, with the skull and lower jaw nearly complete. Many other 

 individuals of the Binocerata were also discovered, and the abundant 

 material tlien collected was sufficient to clear up most of the doubtful 

 points in this group. 



The research was continued systematically during the next season, 

 also, 1874, and again in 1875, with good results. Since then, various 

 small parties, at different times, have been equipped and sent out by the 

 author to collect in this basin ; and, finally, during the entire season of 

 1882, the work was vigorously prosecuted under the direction of the 

 author, and, from July of that year, under the auspices of the United 

 States Geological Survey. 



The specimens thus brought together by all these various expeditions 

 and parties are now in the nniseum at Yale College, and represent more 

 than two hundred individuals of the Diimt'iata alone. Of these, not less 

 than seventy-five have portions of the skull more or less perfectly 

 preserved, and in more than twenty it is in good condition. The present 

 volume is based on this material, amply sufficient, it is believed, to 

 illustrate all the more important parts of the structui'e of this remarkable 

 group. 



The remaining matei'ial of the Dinocerata, now known, consists of a 

 few specimens collected by Dr. Leidy in 1872, including the type of the 

 genus Uintatheriunt ; various remains secured in tlie same year by Prof. 

 Cope, to which he applied the names Loxolophxloii. and Eobasileus, with 

 a later acquisition, called Bathyopsis ; and a number of specimens more 



