Another peculiarity of the head consists in the lower maxillary bones being provided each at its point with a single small and very sharp tooth. These were not noticed during the dissection, owing to their being too much embedded in the integuments.[46]
20971. Barnegat City, New Jersey.—Adult female. The teeth are slender, cylindrical, and irregularly pointed at both ends. The tips show what appears to be an inner core of dentine which has been worn down nearly to the cement coating and somewhat fractured. The cement coating is several millimeters thick, but does not increase the diameter of the teeth near the middle, so that they remain irregularly cylindrical throughout. The surface of the cement is rough and irregular. The root is short, conical, and closed at the end. These teeth are nearly straight. As they have been extracted from the jaw and the latter is broken it is not possible to distinguish which is the upper and which the lower surface, but they are irregularly oval in section, and a little compressed. ([Pl. 38], figs. 3-5.)
In my original notes on this specimen, I recorded that there was a small pair of teeth behind the larger ones described above. Mention of these will be made again later. (See [p. 57].)
22069. Bering Island.—Adult female (?). The teeth are in position in this specimen and are nearly horizontal in position, but a little inclined upward and toward each other. They do not extend beyond the tip of the jaw nor up to the level of the upper surface of the symphysis, but protrude about 13 mm. beyond the alveoli on the side. They are rather slender, somewhat fusiform, blunt at both ends and slightly curved upward. The surface is irregular. They are nearly round in section. The root is closed, and the apex shows what appears to be a core of dentine surrounded by cement. There is a depression on the inner side near the root. These teeth are remarkable as intermediate in form between those of the preceding specimen and those of the specimens next to be mentioned. ([Pl. 38], figs. 6, 7; [pl. 22], fig. 3.)
20993. Bering Island.—Adult male (?). (Type of Z. grebnitzkii.) These teeth are almond-shaped and very symmetrical. They are thickest near the base and taper gradually to the tip, which is quite acute. They are somewhat compressed and hence elliptical in section, the vertical diameter being greater than the transverse diameter. One side (probably the inner) is flattened. They are slightly curved upward toward the apex, which is a little worn and fractured. The root is very short and conical. It is nearly closed, but a very small canal extends upward for about 10 mm. The surface of the tooth is quite smooth, but dull in the lower half. The line of demarcation between cement and dentine is not evident. ([Pl. 38], figs. 8, 9; [pl. 23], fig. 1.)
21248. Bering Island.—Adult male (?). In this specimen the teeth are still in the natural position in the jaw. They are held in place by ligaments and protrude far beyond the alveoli, only about one-ninth of their length being below the superior border. They incline forward at an angle of about 45° with the longitudinal axis of the jaw and diverge slightly at the tips.
The teeth themselves have the same general form as those of the preceding specimen, but are larger. The inner surface is flattened and the outer strongly convex. The tips are quite pointed, but show some indications of wear. The roots can not be seen distinctly, but appear to be closed. ([Pl. 22], fig. 4.)
49599. Newport, Rhode Island.—Adult male. These teeth are longer than those of the preceding specimen, and while they resemble the latter in general form, taper much more gradually to the tip. The root, or portion below the point of maximum girth, is much shorter than that above, and rugose, with several deep furrows. A very small circular opening at the base of the root marks the orifice of the nerve. The upper half of the teeth is smooth, and the tips slightly worn and fractured. The small elliptical worn area is situated on the convex side of the tooth, which appears to be the outer side. As the alveoli of the jaw are, however, filled with a network of bone, the teeth can not be inserted in them. They were detached when received. ([Pl. 38], figs. 10, 11; [pl. 22], fig. 2; [pl. 23], figs. 2, 3.)
Besides the difference in the size and form of the teeth in the two sexes, it is probable, as will be seen by consulting the foregoing data, that in the female the apex of the teeth does not extend more than a very small distance above the alveoli even in mature individuals, and probably often not more than a few millimeters; while in adult males the teeth are almost entirely protruded from the alveoli, which are filled with a coarse bony network. These differences are carried out in all the American specimens, and also characterized the New Zealand specimens, as may be learned from the accounts of Haast and Hector.
A number of rudimentary teeth in addition to the large terminal pair have been noted in the Aresquiers, Buenos Ayres, and perhaps other specimens, and two such teeth were found in the mandible of the Barnegat specimen, behind the large pair. One of these rudimentary teeth has been preserved. It is cylindrical and moderately curved. The length is 16 mm. and the diameter 2 mm. The whole tooth, with the exception of the extreme tip, is thickly coated with cement. The root is closed and the crown acute and apparently abraded by use. ([Pl. 38], fig. 5.)