The Artiodactyla. 1085 
mediate tubercles are less developed than in Dichobune. They 
are related to the twe selenodont genera of CÆNOTHERIIDÆ, Cæno- 
therium and Muillactherium., The latter differs from the former 
in the absence of the intermediate crescent from the last superior 
molars. The species of Cenotherium differ in the absence or pres- 
ence of ashort diastema in the dental series, and in its position in 
the lower jaw, whether behind the first or secondpremolar. (Fic. 4.) 
The Dichobunid bunodont genera are ancestral to the Czenothe- 
riid selenodont genera in the following fashion :— 
Jeenotherium. Muillactherium. 
| Spaniotherium. 
Dilotherium. 
Diehobuune. 
This family terminated with the selenodont genera, which, as 
hlosser remarks, left no known descendants. 
THE ANTHRACOTHERIID# present but few varations. Four 
genera are known, which differ as follows :— 
Entirely bunodont ; no diastemata ; canines developed. Cebochcerus 
ery. 
Cusps of superior molars little flattened ; diastemata ; canine large. 
eropotamus Cuv. 
Cusps of superior mòlars flattened ; no diastemata ; canines large. 
Anthracotherium Cuv. 
Cusps of superior molars crescentoid in section ; diastemata ; canines 
aree i0 alao aea he ks Hyopotamus Owen. 
The three genera last named cannot, as Schlosser remarks, be 
related in direct lines, but through common ancestors ; as may be 
shown thus :— 
Hyopotamus. 
j 
*1/ 
/ 
f 
/ 
Anthracotherium. 
Choeropotamus, 
Cebocheerus. 
