145—4 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
those of the true ruminants, it is highly probable that the more specialized forms of 
the group were endowed with the ruminating function, while in the less specialized 
forms this function was absent. 1 If this be so it is evident that the more specialized 
forms must have been at least as closely related to the true ruminants as to the 
bunodonts, although the oreodons are so connected by M erycopotamus with the 
hippopotamus and the pigs as to clearly form one group, and it, therefore, confirms 
our conclusion as to the intimate relationship existing between the pigs and the true 
ruminants. 
It may be affirmed with more certainty that the food of the higher selenodont 
pigs consisted in great part of leaves and grass (which require finer trituration, and 
consequently a more complex form of molar, as is exemplified in the ruminants, 
horses, and elephants), while their bunodont allies feed, as we know, more generally 
on roots and tubers, and occasionally on animal matter. Elence it is probable that 
the muzzles of most of the selenodonts were less elongated than in the true pigs, 
which require to turn up the soil to obtain their nutriment. 
It must further be observed that certain peculiar and little-known animals 
(Ceboclioenis ) have been described from the Quercy phosphorites, 2 the molar teeth of 
which closely resemble those of the bunodont pigs, while the skulls show certain 
affiinities to those of the simiine Primates, and it is highly probable that these 
animals are related both to the monkeys and the pigs. They have been referred to 
a group termed Pachysimia, but it is doubtful whether this should be placed among 
the Primates nr the Artiodactyla. 
In the following table a provisional scheme for the classification of the best- 
known families and genera of the Suina is given, and the relationship of the section 
to the Ruminantia and Pachysimia is also indicated, but the position of the latter 
section in the Artiodactyla must only be considered provisional. The genus 
Listriodon is purposely omitted, and referred to the perissodactyles ; if, however, it 
really be an artiodactyle, it should probably form a separate family of - the 
Bunodontia. Hippokyus is only provisionally referred to the family Suidce, as its 
molars exhibit a more specialized structure than those of the other members, and it 
should perhaps be raised to the rank of a distinct family. It has not been found 
practicable to indicate in the table all the relationships of the different families to 
one another ; thus the relationship of Hippopotamus to Merycopotamus is not 
apparent ; and while the former genus is placed nearest to the Pachysimia, the 
relationship of that group is evidently nearer to Byotherium and A cotherulum. 
Many of the American, and other, genera are omitted, on account of the difficulty 
of assigning them to their proper positions. 
1 Professor Gaudry (.“ Les Enchainements du Monde Animal ”) classes the oreodons as true ruminants, but Hyopoiamus and 
Merycopotamus as Suina. 
2 Filhol “ Ii&cherches sur Les Phosphorites du Quercy.” ‘Ann. d. Sci. Nat.,’ Vol. VII. (reprint), 1878, p. 327. 
