666 The American Naturalist. [August, 
therium, which was considered by Paleontologists of twenty-five years 
ago, as a primitive form, especially in its foot structure, Anoplotherium 
certainly possesses a number of primitive characters in its manus and 
pes, such as the separation of the metatarsals, and the non-fusion of the 
podial elements, but the inadaptive reduction of its digits, as pointed 
out by Kowalevsky and the peculiar position of the pollux and hallux, 
excludes the possibility of placing Anoplotherium in the direct line 
leading to any of the living Artiodactyla. 
I propose in this short paper to attempt to prove, that Anoplotherium 
has been probably derived from Dacrytherium, a closely allied genus, 
but whose foot structure is normal and which resembles that of many of 
the early Eocene Artiodactyla such as Cainotherium. Prof Cope' sug- 
gested that Cebochwrus may have been the ancestor of Anoplotherium, 
but the structure of the skull in Cebocherus, is already quite modern- 
ized, nearly as much so as in the true pigs, consequently I am inclined 
to think that we shall have to look for some other form as ancestral to 
Anoplotherium. 
The general form of the skull in Daerytherium is like that of Anoplo- 
therium, however, in Dacrytherium there is a strongly pronounced pre- 
orbital fossa, which is absent in Anoplotherium. The crowns of the 
upper teeth in Dacrytherium are low and primitive in structure. They 
exhibit rounded external crescents, which are not at all angular. In 
Anoplotherium, especially the large species, the crowns of the superior 
true molars are more lengthened than in Dacrytherium and the external 
crescents are angular and broad. We see this change in many mam- 
malian phyla from extremely low crowned molars, to those which are 
tending to the hypselodont condition. As regards the intermediate 
stage, between Dacrytherium and Anoplotherium, as to the height of 
the molars, this is found in the genus Diplobune. 
The lower true molars of Daerytherium exhibit two internal cones, 
which is the normal number in the Artiodactyla. It is interesting to 
record, that I have noticed in a number of young jaws of Dacrytherium 
in which the true molars were just coming through, that the antero- 
internal cusp, which is single in the adult, shows a slight reduplication, 
which is the normal condition in Diplobune. The division of the meta- 
conid is carried still further in the largest species of Anoplotherium, 
although I have examined many jaws from the Phosphorites of the 
Anoplotherium, and I can confidently state, that all gradations exist 
between the complete isolation of the two antero-internal cusps of the 
typical forms of Anoplotherium, and the single condition of these cusps, 
1 Artiodactyla, AMERICAN NATURALIST, Dec., 1888, p. 1083. 
