As touching that curious creature, the Crested, or Hooded Seal (_Cystophora cristatus_), a native of the colder regions of the North Atlantic. This animal is remarkable for the development, in the males alone, of a great crest or casque on the head, which is formed by a large inflatable air-sac over the ridge of the nose, and communicating with the nostrils. When fully inflated, it covers the head as far back as the eye. Its purpose is a matter of conjecture. It seems to be inflated either when he animal is greatly excited, as when challenging rival males, or when threatened with danger from other causes, as when attacked by man. The males are exceedingly pugnacious, and fight with one another for the possession of females with great ferocity, such contests being accompanied by cries which can be heard for miles. From the difficulty which Esquimaux and sealers find in killing the animal with clubs it certainly seems as if this strange wind-bag were more than merely ornamental. [Illustration: Plate 14. _Photo copyright, W. P. Pycraft._ ELEPHANT SEAL. This is a young animal. Note the great size of the eyes, and the general “seal-like” character of the head as compared with that of the adult.] [Illustration: _Photo by courtesy of Charles Haskins Townsend, Director of New York Aquarium._ NORTHERN ELEPHANT SEAL. Adult male and female, and yearling. The male shows the enormously inflated snout. [Face page 88.] That those extraordinary creatures the Cetacea—the Whales and their kin—are derived from the same common stock as the typical carnivora there can nowadays be no doubt, widely as they have departed from their land-dwelling relatives in almost every possible feature of their organization. In the matter of their “Courtship” we know nothing, but we may infer certain incidents in this critical period of their life-history from the peculiar nature of the secondary sexual characters which some species display. Thus in the Pilot Whale (_Globicephalus_) and the Bottle-nose Whale (_Hyperoödon_) the forehead, in the bulls, is enormously swollen by a mass of fibrous tissue so dense as to turn the blade of the sharpest knife, as I know well from attempts to dissect this region. Now the only use, surely, for such a cushion is that of a battering-ram by rival males in charging one another, as rams and other horned animals will do. In the Bottle-nose Whale this cushion is backed up by an enormous mass of solid bone thrown up by the maxillæ. The origin of this bony growth is interesting, for it appears first as a slight swelling in the rare species _Berardius_; it is seen at a further stage of growth in the female “Bottle-nose” (_Hyperoödon_), and attains its maximum in the male, where it stands unique. There are two other species which demand notice here. The first is Layard’s Beaked Whale (_Mesoplodon_); the second the Narwhal. The former is the only vertebrate which in a wild state wears a muzzle! In this species the teeth have totally vanished