372

HALITHERIUM.

molar series, none of them being displaced by vertical successors:in this respect it manifests, like the Dugong, a cetaceous character,and the more strongly, inasmuch as the number of molars succes-sively developed from before backwards is greater. The anteriorteeth are, however, displaced before the posterior ones are developed,although they have no vertical successors, which circumstance is alsocharacteristic of the Elephant : the shape, the structure, and the modeof implantation of the molars of the Manatee quite accord with thepachydermal type, and herein more especially with the Dinotheriumand Tapir.

149. Halitherium{ 1).—An extinct herbivorous Cetacean has beendiscovered in the miocene tertiary deposits which resembles the Dugongin many parts of its skeleton, and in having permanent tusks in theupper jaw : but which has complex, ridged, enamelled and many-rootedmolars as in the Manatee. The grinding surface of these teethoffers a slight modification of form; the superior molars when firstfound detached were referred by Cuvier to the Hippopotamus dubius:the lower molars to the Hippopotamus medius. The latter, PI. 97,fig. 5, have three tuberculate ridges, the posterior one the smallest ;when worn down the crown of the tooth presents three pairs ofrounded lobes, and its margins are deeply festooned. The uppermolars (fig. 4) are more square-shaped, and the third tubercular ridgeis almost obsolete.

In a second species of the same or a nearly allied genus(Halitherium Brochii ) the crowns of the teeth are more rounded,and beset with tuberculated mammiliform eminences. The entireseries on the left upper jaw is showm in PI. 97, fig. 1, and a similarseries of three molars in the left ramus of the lower jaw of theHalitherium Cuvieri (fig. 2). The ultimate discovery and restorationof a great part of the skeleton of one of the species ( HalitheriumCuvieri ), and the determination of the small number of molar teethin both species, have established a very interesting intermediate genusbetween Halicore and Manatus, and, at the same time, one whichpushed its infinities much nearer than either of the existing generatowards the pachydermal aquatic genus Hippopotamus.

(1) Metaxytherium, Christo], Cheirolherium, Bruno.