The dentition of the Cynoidea is most closely linked with that of the Arctoidea by means of fossil forms.

Fig. 85. Mandible of Isabelline Bear (Ursus isabellinus) × ½.

(Camb. Mus.)

1. condyle.m 1. first molar. The dotted
2. coronoid process.line is pointing to the posterior
i 1. first incisor.half of the tooth.
c. canine.This specimen has only
pm 1, pm 2. first and secondthree premolars, there
premolars.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.

Fig. 86. Left mandibular ramus of the Sea Leopard (Ogmorhinus leptonyx)

WITH THE ROOTS OF THE TEETH EXPOSED × 1/3. (Camb. Mus.)