174 ON THE EXTINCT MAMMALIA OP 



AETIODACTTLA. 



The above term, first employed by Prof. Owen of London, I have adopted as the 

 name of an order including the even-toed animals of the order of Pachydermata of 

 Cuvier, and excluding the Rurainantia of the Pachydermata Artiodactyla of Owen. 

 As thus restricted, the order is represented in the tertiary formations of Dakota and 

 Nebraska by eight species of seven genera, all of which are extinct except one, — the 

 genus Dicotyles. Two of the genera, Hyopotamus and Titanoiherium, belong to the 

 lowest bed of the miocene formation of the Mauvaises Terres of White River, Dakota, 

 indicated as bed A in Dr. E^ay den's table, page 21. The other genera, Elotherium, 

 &c., belong to intermediate beds of the same formation and locality, indicated as beds 

 B and D in Dr. Hayden's table. The species of Dicotyles is represented by a single 

 tooth from the sands of the Niobrara River, Nebraska, the position being indicated 

 as bed F of the pliocene formation in Dr. Hayden's tables, pages 16 and 21. 



EVTDM. 

 ELOTHERIUM. 



Elotherium is an extinct genus of remarkable animals belonging to the family of 

 suilline pachyderms. It was first indicated in 1847 by M. Pomel, from some remains 

 found in the Department of the Gironde, France. The following year it was more 

 completely characterized, under the name of Entelodon, by M. Aymard, from remains 

 discovered together with othei's of Hycenodon, Hyopotamus, Sec, in a formation at 

 Rongon, in the Department of the Haute-Loire. Its allies among extinct genera are 

 ChoerojMtamiis, Palceochcerus, Anthracotherium, etc. ; among recent animals, the Hog, 

 Peccary and Hipjjopotamus. 



A species, apparently of the same genus, was characterized in 1850 in the Proceed- 

 ings of this Academy, under the name of Archceotherium Mortoni. It was proposed 

 on a specimen consisting of a fragment of an upper jaw containing two premolars, 

 obtained in the Mauvaises Terres and presented to the Academy by Mr. Alexander 

 Culbertsou. 



The original descriptions of Elotherium by M. Pomel, and Entelodon by M. Aymard, 

 I have not had the opportunity of seeing, nor had I seen any account of them at the 

 time of publishing a notice of Archaiotheriiim. 



