In the Cynoidea[163] the general dentition is _i_ 3/3 _c_ 1/1 _pm_ 4/4 _m_ 2/3, total 42. This differs from the regular mammalian dentition only in the absence of the last upper molar. The upper carnassial tooth (fig. 84, II.) consists of a larger middle and smaller posterior lobe with hardly any trace of an anterior lobe. The lower carnassial (fig. 84, V.) is typical, consisting of a bilobed blade with inner cusp and posterior talon. The dentition of the Cynoidea is most closely linked with that of the Arctoidea by means of fossil forms. [Illustration FIG. 85. MANDIBLE OF ISABELLINE BEAR (_Ursus isabellinus_) × 1/2. (Camb. Mus.) 1. condyle. 2. coronoid process. _i_ 1. first incisor. _c._ canine. _pm_ 1, _pm_ 2. first and second premolars. _m_ 1. first molar. The dotted line is pointing to the posterior half of the tooth. This specimen has only three premolars, there should be four.] In the Arctoidea the dentition is not so typically carnivorous as in the Æluroidea and Cynoidea. In the bears, Ursidae, the molars have broad flat tuberculated crowns (fig. 85). The dental formula in _Ursus_ is _i_ 3/3 _c_ 1/1 _pm_ 4/4 _m_ 2/3, total 42. The upper carnassial (fig. 84, III.) differs from that of the Æluroidea and Cynoidea in having no inner lobe supported on a third root. In the large group of Mustelidae there are generally two molars in the lower and one in the upper jaw. The grinding teeth commonly have large, flattened, more or less tuberculated crowns, and the upper molar may be as large or much smaller than the carnassial. In the _CREODONTA_ there are no specially differentiated carnassial teeth. [Illustration FIG. 86. LEFT MANDIBULAR RAMUS OF THE SEA LEOPARD (_Ogmorhinus leptonyx_) WITH THE ROOTS OF THE TEETH EXPOSED × 1/3. (Camb. Mus.) 1. condyle. 2. coronoid process. _i_ 3. third incisor. _c._ canine. _pm_ 1, _pm_ 4. first and fourth premolars. _m._ molar.] In the _PINNIPEDIA_ the dentition differs considerably from that of the Carnivora vera. The milk dentition is always vestigial, and the teeth are frequently absorbed before birth. There are four premolars and one molar, forming an uniform series of cheek teeth, all of which except in the Walrus have compressed and pointed, never flattened, crowns. There is no special carnassial tooth, and the incisors are always fewer than 3/3. In _Otaria_ the dentition is _i_ 3/2 _c_ 1/1 _pm_ 4/4 _m_ 1 or 2/1, total 34 or 36. In the Walrus the upper canines form immense tusks. The other teeth are all small and one-rooted, and the molars have flat crowns. In the true seals the dentition is strikingly piscivorous, the cheek teeth often having accessory cusps (fig. 86).