Posterior tooth quite irregular in form, but the portion above the rugose base or root conical. Inner surface flat and uneven. Outer surface convex and rather rugose. The cement covers the whole tooth thickly to within about 5 mm. of the apex, which latter is short, quite acute, and slightly directed inward. It is convex externally and nearly flat internally. The basal rugosity or root is conical, thicker than the rest of the tooth, and unsymmetrical, being somewhat directed backward. It shows no opening below. When in the natural position this tooth is strongly inclined forward and outward, and only the tip for a length of 22 mm. protrudes beyond the alveolus. (Pl. 39, fig. 6.) _No. 49726._—St. George Island, Alaska; female, adult. Anterior tooth conical, with the tip blunt, having been so much abraded that the dentine does not extend beyond the coating of cement. The tip measures 26 by 19 mm. The external and internal surfaces of the tooth are about equally convex and somewhat rugose without distinct furrows. The root is thicker than the remainder of the tooth and very rugose. It is entirely closed below, and the inferior outline is convex. Posterior tooth much compressed, conical above the root, nearly flat internally and slightly convex externally. Cement coating very thick and extending to within about 5 mm. of the dentine apex, which latter is acute and very slightly curved inward and backward. The root is very unsymmetrical, the posterior portion being much longer than the anterior. The surface is very rugose, and there is no opening whatever below. The inferior border is convex, with an emargination near the center. (Pl. 39, figs. 7, 8.) In the adult skull from Bering Island, which has been mounted and placed on exhibition, the teeth are fixed in the alveoli so that their entire length and the peculiarities of the basal portion can not be determined. In general form, however, they resemble those of the preceding specimen very closely. The anterior teeth are placed obliquely—that is, so that the anterior margins of the two teeth are nearer together than the posterior margins. The teeth are also somewhat inclined forward. The posterior teeth are strongly inclined forward and a little outward. The anterior teeth are rather concave along the middle internally and convex externally. The portion above the alveoli is quite smooth. The posterior teeth are moderately rugose above the alveoli. The whitish tips of denture are conical, compressed, and rather acute. They extend 6 mm. above the denture, and are 11 mm. long at their base, and 6 mm. thick.