Cope.] 188 [Dec. 16, 



The characters of the .tarsus are of much interest, and demonstrate that 

 Modcenus is the oldest type of artiodactyle yet discovered, and that it is 

 not altogether primitive in some of its characters. Members of this order 

 have been found by Cuvier in the upper Eocene {Dichobune^ Anoplotherium, 

 etc.), but none have been determined as yet from the Suessonian of 

 America. A species represented by teeth from the Siderolithic beds of 

 Switzerland have been referred to Dichobune (C. campichii Pict.) ; 

 but dental characters alone are not sufficient to distinguish that genus 

 from PJienacodontidm*. Dr. Lemoine found astragali of a small Artiodactyle 

 in the Suessonian of Reims, and has referred them to his supposed Suil- 

 line Lophiochmrus peroni. I have reported an astragalus from the Wind 

 River formation of Wyoming Territory, which is almost exactly similar to 

 those found by Lemoine. The specimen now described, enables me to 

 characterize with some degree of completeness this interesting form, which 

 precedes in time all the known American Artiodactyla. 



The characters of the tarsus are typically those of the order Artiodactyla. 

 The astragalus exhibits a distal trochlea which is continuous with the 

 sustentacular facet, and which articulates with both cuboid and navicular. 

 The distal portion of the fibula is free from the tibia, and its shaft becomes 

 very slender. It is possible that a more perfect specimen would dis- 

 play it as continuous, Its distal extremity articulates with the ascending 

 tuberosity of the calcaneum. The cuboid facet of the latter is narrow. The 

 cuboid and navicular bones are distinct from each other and from the 

 cuneiforms. The mesocuneiform is shorter than the ectocuneiform, and 

 is coossified with it. There are probably four metatarsals. The median 

 pair are distinct, but appressed, their section together, sub-circular. The 

 ateral metatarsals are slender, the external one is wanting, but its facet 

 on the cuboid bone is very small. 



These characters are in general similar to those of the genus Dichobune, 

 but Cuvier f does not state whether the cuneiforms are coossified in that 

 genus or not. They are united in Anoplotherium. % Mioclcenus differs 

 from Dichobune in the presence of but one internal tubercle of the superior 

 molars, and in the single external tubercle of the superior premolars. Both 

 genera are referable to a family to be distinguished from the Anoplotheriidcs 

 by the presence of the external digits. This has been already named by 

 Gill the DicJtobunidae. 



Char, specif. The bones are about two thirds the size of those of the 

 Javan musk deer (Tragulus javanicus). The transverse extent of the 

 superior true molars is greater than the anteroposterior. The composition 

 of the last molar is like that of the others. The external tubercles are 

 lenticular in section and the emargination which separates them is ap- 

 parent on the external face of the crown. The intermediate tubercles are 

 small, and are entirely distinct from the large external tubercle. There 



* See American Naturalist, 1881, December. 



t Ossemens Fossiles, v, p. 183. 



JGaudry Enchainements d. Regne Animal, p. 147, 



