DAKOTA AND NEBRASKA. 



141 



Series upper true molars, 

 Antero-poslerior diameter 

 Transverse " 



Antero-posterior diameter 

 Transverse " 



Antero-posterior diameter 

 Transverse " 



Antero-posterior diameter 

 Transverse " 



Series lower true molars, 

 Antero-posterior diameter 

 Transverse " 



Antero-posterior diameter 

 Transverse " 



Antero-posterior diameter 

 Transverse " 



Antero-posterior diameter 



of last true molar,* . 



it n 



of second true molar, 

 (( ti 



of first true molar, 



of last premolar, 

 it ti 



of last true molar, 

 tt ti 



of second true molar, 

 (( it 



of first true molar, 

 (( it 



of last premolar, 



Measurements in lines. 



A. latifrons. A. antiquus. Agrioc. Agrioc. Agrioc. A. major 



22 

 9 



8} 



9 



61 



7 

 5 J 



24 



lU 



6 



7 



5 J 

 5i 

 5 

 5i 



221 



9 

 lOi 



8 



9 



61 



71 



6 



61 

 25 

 12 



6 



7 



61 



61 



5 



61 



221 

 8J 

 91 

 81 

 9 

 7 



7i 

 51 

 61 



111 

 6 



22i 

 9i 



101 

 81 



10 



6 

 6i 



12J 

 61 



71 

 5J 



91 

 lOi 



81 



131 

 61 

 8 

 6 



81 

 6 



GAMELIDJE. 



This family, represented in the recent fauna of the earth by the Camel and Lama, 

 contained many more representatives in former geological eras. In the fauna under 

 investigation it ajipears to have been well represented. The remains viewed as be- 

 longing to it have been referred to six extinct genera, comprising eight species. 



Two of the genera are of the miocene period ; the remains of one — Pcehrotherium — 

 having been obtained from bed B of Dr. Hayden's section, in association with remains 

 of Oreodon Calbertsoni, etc. The fossil upon which the genus Protomeryx was founded 

 was obtained from bed D of the same section. The other genera belonged to the 

 pliocene period, — the remains of three species o? Pi-ocamelus, and those oi Homocamelu-s, 

 Megalomeryx and Merycodus having been obtained from bed F of Dr. Hayden's 

 section. 



PCEBROTHERIUM. 



The name Pcebrotlierium is applied to an extinct genus of ruminating animals, 

 apparently most nearly allied to the Camel and Lama among existing animals. 



PCEBROTHERIUM WlLSONI. 



A unique species, to which the above name was given, was established on a speci- 

 men consisting of the facial portion of a skull from the Mauvaises Terres of "White 



* The antero-posterior diameter is taken between the most prominent points externally in the case of the 

 upper teeth, internally in the lower teeth. The transverse diameter is talien between the most promineat 

 points anteriorly. 



