This extraordinary genus, which can be compared to nothing in living nature, is subdivided into three subgenera: the Anaplotheria, properly so called, the anterior molares of which are still pretty thick, and the posterior ones of the lower jaw have their crescents with a simple ridge; the Xiphodons, of which the anterior molares are thin and sharp on the edges, and the under posterior, have, directly opposite the concavity of each of their crescents, a point, which, on being worn, also assumes the form of a crescent, so that then the crescents are double as in the ruminantia; lastly, the Dichobunes, the outer crescents of which are also pointed at the beginning, and which have thus points disposed in pairs upon their lower posterior grinders.

The most common species in our gypsum quarries (An. commune), is an animal of the height of a boar, but much more elongated, and furnished with a very long and very thick tail, so that altogether it has nearly the proportion of the otter, but larger. It is probable that it was well fitted for swimming, and frequented the lakes in the bottom of which its bones have been incrusted by the gypsum which was deposited there. We have one a little smaller, but in other respects pretty similar (An. secundarium.)

We are as yet acquainted with only one xiphodon, which, however, is a very remarkable animal: it is that which I have named An. gracile. It is slender, and delicately formed, like the prettiest gazelle.

There is one dichobune, nearly of the size of a hare, to which I have given the name of An. leporinum. Besides its subgeneric characters, it differs from the anaplotheria and xiphodons, in having two small and slender toes on each foot, at the sides of the two large toes.

We do not know if these lateral toes exist in the two other dichobunes, which are small, and scarcely exceed in size the common Guinea pig[274].

The genus of Anthracotheria is in some degree intermediate between the palæotheria, anaplotheria, and hogs. I have named it so, because two of its species have been found in the lignites of Cadibona, near Savone. The first approached the rhinoceros in size; the second was much smaller. They have also been found in Alsace, and in the Vélay. Their grinders are similar to those of the anaplotheria; but they have projecting canine teeth[275].

The genus Cheropotamus is found in our gypsum deposits, where it accompanies the palæotheria and anaplotheria, but where it is of much rarer occurrence. Its posterior grinders are square above, rectangular below, and have four large conical eminences surrounded with smaller ones. The anterior molares are short cones, slightly compressed, and with two roots. Its canine teeth are small. Neither its incisors nor its feet are yet known. I possess only one species, which is of the size of a Siam hog[276].

The genus Adapis has also but one species, which is at most of the size of a rabbit: it is also from our gypsum quarries, and must have been nearly allied to the anaplotheria[277].

We have thus nearly forty species of pachydermata belonging to genera now entirely extinct, and presenting forms and proportions to which there is nothing that can be compared in the present animal kingdom, excepting two tapirs and a daman.

This large number of pachydermata is so much the more remarkable, that the ruminantia, which are at present so numerous in the genera of deer and antelopes, and which attain so great a size in those of the oxen, giraffes, and camels, scarcely make their appearance in the deposits of which we are speaking.