In _Toxodon_ the upper incisors and molars are large and curved and all the teeth have persistent pulps. In _Typotherium_ there are no tusks, but the upper incisors are chisel-like, recalling those of Rodents. The _CONDYLARTHRA_ have brachydont, generally bunodont teeth, with the premolars simpler than the molars. They generally have the regular dental formula. _HYRACOIDEA._ The dental formula of _Procavia_ is usually given as _i_ 1/2 _c_ 0/0 _pm_ 4/4 _m_ 3/3, total 34; in young individuals however there occur a second pair of upper incisors which early fall out. The upper incisors resemble those of Rodents in being long and curved and growing from persistent pulps. They are however triangular in transverse section, not rectangular, having two antero-lateral faces covered with enamel and a posterior face without enamel. Their terminations are pointed, not chisel-shaped as in Rodents. The lower incisors (fig. 83, _i_ 1) are pectinate or partially divided by vertical fissures, and the grinding teeth are of the rhinocerotic type. [Illustration FIG. 83. SKULL OF _Procavia (Dendrohyrax) dorsalis_ × 2/3. (Camb. Mus.) 1. nasal. 2. parietal. 3. external auditory meatus. 4. paroccipital process of the exoccipital. 5. jugal. 6. lachrymal foramen. _i_ 1. first incisor.] _AMBLYPODA._ Two of the best known forms belonging to this extinct group differ much as regards dentition. For while _Coryphodon_ has the regular dental formula, and the canines of both jaws of moderate size, in _Uintatherium_ the dentition is very specialised, there are no upper incisors, and the upper canines form a pair of enormous tusks. The grinding teeth form a continuous series marked by =V=-shaped ridges and the dental formula is _i_ 0/3 _c_ 1/1 _pm_ 3/3 _m_ 3/3 total 34. _PROBOSCIDEA._ The incisors are composed entirely of dentine and have the form of conical tusks projecting greatly from the mouth. In living forms they are confined to the upper jaw, in some species of the extinct _Mastodon_ however they occur in the lower jaw also. In _Dinotherium_ they are probably absent from the upper jaw, but form a pair of downwardly and backwardly-directed tusks growing from the elongated symphysis of the mandible.