We disposed of the land Carnivora in the last article, and now, before proceeding to the Cetacea, I will give a slight sketch of the marine Carnivora, of which, however, no examples are to be found on the Indian coasts. The Pinnipedia or Pinnigrada are amphibious in their habits, living chiefly in the water, but resorting occasionally to the land. There are some examples of the land Carnivora which do the same—the polar bear and otter, and more especially the sea-otter, Enhydra lutris, which is almost exclusively aquatic, but these are all decidedly of the quadrupedal type, whereas in the amphibia we see the approach to the fish form necessary for their mode of life. The skeleton reveals the ordinary characteristics of the quadruped with somewhat distorted limbs. The bones of the forelimbs are very powerful and short, a broad scapula, short humerus and the ulna and radius are stout, parallel to each other, and the latter much broader at the base; often in old animals the two are ankylosed at the joint, which is also the case with the tibia and fibula. The hip-bones are narrow and much compressed, the femur remarkably short, the shank-bones and the bones of the feet very long. In walking on land the feet are, in the case of the Otaria or eared seals placed flat on the full sole; the common seals never use their hind limbs on the shore. The dentition is essentially carnivorous, but varies considerably in the different families, and even in the Phocidæ themselves. The stomach is simple, but the intestines are considerably longer than in the Felidæ, averaging about fifteen times the length of the body; the digestion is rapid. The bones are light and spongy, and the spine particularly flexible, from the amount of cartilage between the bones. They have a large venous cavity in the liver, and the lungs are capacious, the two combining to assist them in keeping under water; the blood is dark and abundant. The brain is large, and in quantity and amount of convolution exceeds that of the land Carnivores. Their hearing is acute, but their sight out of water is defective.
Their external features are an elongated pisciform body, the toes joined by a membrane converting the feet into broad flippers or fins, the two hind ones being so close as to act like the caudal fin of a fish. The head is flattish and elongated, or more or less rounded, but in comparison with the body it is small. Except in the Otaridæ there are no perceptible ears, and in them the ear is very small. The fur is of two kinds, one long and coarse, but the other, or under fur, is beautifully soft and close, and is the ordinary sealskin of commerce. The roots of the coarse hair go deeper into the skin than those of the under fur, so the furrier takes advantage of this by thinning the skin down to the coarse roots, cutting them free, and then the hairs are easily removed, leaving the soft fur attached to the skin.
The Pinnigrada are divided into three families—the Trichechidæ, or walruses; the Otaridæ, or sea-lions or eared seals; and the Phocidæ, or ordinary seals.
As none of these animals have been as yet observed in the Indian seas, being chiefly denizens of cold zones, I will not attempt any further description of species, having merely alluded to them en passant as forming an important link in the chain of animal creation.
We must now pass on to the next order, a still more aquatic one.
[ORDER CETACEA—THE WHALES.]
These curious creatures have nothing of the fish about them, save the form, and frequently the name. In other respects they are warm-blooded, viviparous mammals, destitute of hinder limbs, and with very short fore-limbs completely enclosed in skin, but having the usual number of bones, though very much shortened, forming a kind of fin. The fin on the back is horizontal, and not rayed and upright like that of a fish; the tail resembles that of a fish in form, the caudal vertebræ running through the middle of it. The immense muscular power of this tail, with its broad flanges, arises from the flesh of the body, terminating in long cords of tendon, running to the tip. The vertebral column is often ankylosed in the fore-part, but is extremely elastic, owing to the cartilaginous cushion between each bone in the latter half. Thus, whilst the fore-part is rigid, the hinder is flexible in the extreme. The brain is large and much convoluted; the heart is very large, and the blood-vessels extremely full and numerous, with extensive ramifications, which, being filled with oxygenated blood, assist in supporting life whilst submerged. The lungs are also very large. The laryngeal and nasal passages are peculiar. The following description is by Dr. Murie: "In front of the larynx of man we all know that there is an elastic lid, the epiglottis, which folds over and protects the air passage as food is swallowed. The side cartilages constitute the walls of the organ of voice and protect the vocal chords. Now, in the comparatively voiceless whale, the cartilages, including the epiglottis, form a long rigid cylindrical tube, which is thrust up the passage at the back of the palate in continuity with the blow-hole. It is there held in place by a muscular ring. With the larynx thus retained bolt upright, and the blow-hole being meanwhile compressed or closed, the cetacean is enabled to swallow food under water without the latter entering the lungs." The stomach is peculiar, being composed of several sacs or chambers with narrow passages between; the intestines are long, glandular and, according to Dr. Murie, full of little pouches. There is no gall bladder; the gullet is very narrow in some and wider in others. Some have teeth, others are without. The eyes are small; the ears deficient externally, though the interior small ear-bones of ordinary mammals are in these massive and exceedingly dense, so much so, as Murie observes, as to be frequently preserved fossil when other osseous structures are destroyed.
The cetacea have been divided into the Denticete, or Toothed Whales, and the Mysticete, or Whalebone Whales. The former contains the river dolphins, the ziphoid whales, the gigantic sperm whale, the sea dolphins, and the narwhal or sea unicorn. The latter contains the baleen whales.