_No. 142118._—Bering Island; young (new born?). Anterior tooth conical, hollow, with thin walls. The lower half of the tooth is filled with a mass of bony pulp, which is separable. The tooth is widest at the base, and is without any constriction indicating the formation of a root. Outer and inner surfaces slightly convex, the latter with several distinct longitudinal furrows, which extend to the apex. The whole tooth has a thin coating of cement, except the tip, for a length of about 10 mm., which is more nearly white, and consists, presumably, of dentine. The tooth is very symmetrical, but rather more convex externally. The apex is pointed, erect, and a little more convex externally than internally. (Pl. 39, figs. 1, 2.) The posterior tooth is similar to the anterior one, but much shorter and more blunt, and the longitudinal furrows are about equally distinct externally and internally. The cement extends nearly to the apex, which latter is very short and is directed backward. _No. 49727._—St. George Island, Alaska; male, immature. Anterior teeth conical, acute, somewhat unsymmetrical, rather more convex externally than internally. The internal surface with a deep median longitudinal groove, and others less distinct on each side near the base. Apex slightly inclined forward and inward, convex externally, with a single longitudinal groove; nearly flat internally, with, or without, a groove. Base of tooth for about 17 mm. covered with longitudinal rugosities, indicating that the root was about to close. It is open, however, the walls of the tooth at the narrowest point being 8 mm. apart and the cavity filled with dense bony pulp. The anterior and posterior outlines of the teeth are irregular, being convex near the base, then slightly concave, and again convex near the apex. When in the natural position, these teeth protrude about 33 mm., or a little more than one-third their height, above the alveolus. (Pl. 39, figs. 3, 4.) Posterior teeth lacking. _No. 49725._—Centerville beach, California; male (?), adult. Anterior tooth conical, with anterior and posterior margins as in the last. Apex considerably abraded and rounded off; not inclined inward or forward. Internal and external surfaces nearly equally convex, but the former with a broad median longitudinal groove. Root closed, the base of the tooth for a breadth of about 30 mm. covered with rounded rugosities. The inferior border slightly convex and the angles rounded off. When in the natural position, somewhat more than one-half of the tooth protrudes beyond the alveolus, and the tooth itself is inclined forward and outward. (Pl. 39, fig. 5.)