TONGUE AND BACK PARTS OF MOUTH OF OTARIA.
(Reduced after Murie.)
to, Right Tonsil; u, Uvula, or Curtain; T, Tongue.
I.—THE WALRUS FAMILY (TRICHECHIDÆ).
This family in some points resembles the Eared Seals, or Otaries, and in others approaches the Earless Seals, or Phocidæ. The characters of the family are mainly, if not wholly, derived from the Walrus, the only living representative. There are no external ears, but a fair-sized opening indicates the passage. Both sexes, when adult, possess two immense tusks in the upper jaw, quite a notable feature. Along with this, there is full development of the bony parts to accommodate them, and the huge, though abruptly truncated muzzle, is garnished with long and remarkably strong bristly moustaches. The semilunar-shaped nostrils, situated above these, are dilated or powerfully compressed at will, by the thick, fleshy muscles of the upper lip. The eye is smaller than in the Otariidæ and Phocidæ. The body, especially its hinder part, is also heavier. The tail seems absent, though, in reality, nearly reaching to the heels, but a broad flap of skin stretches across from leg to leg, and binding these, hides the tail. The hind limbs appear shorter than in the two neighbouring families, but the above tail-membrane is wider, and allows greater freedom to the legs and feet. The three middle toes are shortest, as is the case with the Common Seals, but not the Otaries. The fore-legs are of intermediate length, strong, stumpy, and although the thumb is biggest, there is a certain equality in the length of the toes. The fore feet, as well as the hind feet, are sufficiently free to be laid flat on the ground. The nails are diminutive, and not claw-like, and the soles of the feet are unusually rough and warty. The tongue is smooth, and not cleft at the tip. The dental series is as follows:—Incisors, 1–1 0–0; canines, 1–1 1–1; premolars, 3–3 3–3; molars, 2–2 1–1 = 24. The tusks, or upper canines, lie outside and almost in front of the dental arch. The incisor and grinding teeth are uncommonly alike, being short, cylindrical, and obliquely truncated at their crowns. The teeth alone are very distinctive of this family, and modified for uses and a diet sui generis. There is no such development of a thick coating of under-fur, as in certain of the Otary family, the root hairs being sparse, and the larger sort softer, shaggier, and not so close pressed as in the Seals.
HEAD OF WALRUS.
(Modified after Murie.)
SKULL AND DENTITION OF WALRUS.
(After De Blainville and Murie.)