of the World326 The Living Animals

may seem when viewed from behind the bars of its den in a zoological garden, it is nevertheless true that, when these animals have been banished from an African river by the progress of civilisation, that river has lost one of its highest charms and greatest ornaments. The PYGMY or LIBERTAN HIPPO- POTAMUS is confined to Upper Guinea, and, compared with its only existing relative, is a very small animal, not standing more than 2 feet 6 inches in height, and measuring less than 6 feet in length. In weight a full-grown specimen will scale about 400 Ibs. But little is known of the habits of this rare animal, specimens of which, I believe, have never been obtained, except by the German naturalists Herrn Biittikofer and Jentink. When alive, the colour of the skin of the pygmy hippopotamus Photo by York 0; Son} [Notting Hill. MALE AND FEMALE HIPPOPOTAMUSES. is said to be of a greenish black, ; it never goes farther away changing on the under-parts to A hippopotamus is almost inseparable from the water than possible from a river or lake. yellowish green. The surface of the skin is very shiny. This species, unlike its giant relative, does not congregate in herds, nor pass its days in rivers or lakes, but lives in pairs in marshes or shady forests. It sleeps during the day, and at night wanders over a great extent of country, eating grass, wild fruits, and the young shoots of trees. Its flesh is said to be very succulent and much esteemed by the natives. of the same species as that now found in Africa, formerly A hippopotamus, apparently inhabited the Thames Valley. Great quantities of fossil remains of another species are also found in the island of Sicily. The bones found in England are mainly in the river gravel and brick earth of the south and midland districts of England. This seems to show that at all the year, and not the time when the animal existed our rivers rnust have been open ice-bound, for it is certain that no hippopotamus could live in a river which froze in winter. Yet among the remains of these animals are also found those of quite arctic species like the Musk-ox and the Eeindeer, together with those of the Saiga Antelope, an inhabitant of the is: How could these creatures, one a dweller in warm cold plateau of Tibet. The problem rivers and the others inhabitants of cold arctic or sub-arctic regions, have existed together, ? The answer, which does not seem to have occurred apparently on the same area of ground to naturalists who have discussed the question, seems to be plain enough. Any one who knows the conditions of the great rift valleys of Central Africa has the key to the solution of the puzzle. There was probably a very great difference in the vertical plane. Deep in the rift was probably a warm river, while above it may have been mountains from 10,000 to 20,000 feet high, with snow on the summits and glaciers in their valleys. On these cold and arctic heights the reindeer and the musk-ox would find congenial homes. Thousands of feet below, in the hot and narrow valley, the hippopotamus would revel in a warm and steamy climate. This is what actually occurs in the rift valleys of Central Africa, where the hippopotamus swims in rivers that are at no great distance from snow-covered and ice-capped mountains.

CHAPTER XX.

THE DUGONG, MANATEES, WHALES, PORPOISES, AND DOLPHINS.

BY F. G. AFLALO, F.Z.S.

THE DUGONG AND MANATEES.

r 1 1HESE curious creatures, which seem to have been the basis of much of the old mermaid JL legend, have puzzled many eminent naturalists. Before they were placed in an order by themselves, Linnaeus had classed them with the Walrus, Cuvier with the Whales, and another French zoologist with the Elephants. They are popularly regarded as the cows of the sea-pastures. Their habits justify this. I have often watched dugongs on the Queensland coast browsing on the long grasses, of which they tear up tussocks with sidelong twists of the head, coming to the surface to breathe at short intervals.

Omitting the extinct Ehytina, otherwise known as Steller's Sea-cow, which was exterminated in the Bering Strait not very long after civilised man had first learnt of its existence, we have to consider two distinct groups, or genera, of these sirenians. The DUGONG is the representative of the first, and the two MANATEES belong to the other.

The dugong is found on the coasts of Northern Australia, in many parts of the Indian Ocean (particularly off Ceylon), and in the Eed Sea. It is easily distinguished, by even superficial observation, from the manatees. Its tail is slightly forked, somewhat like that of the whales: the tail of manatees, on the other hand, is rounded. The dugong's flippers, to which we also find a superficial resemblance in those of the whale, show no traces of external nails: in those of the manatees, which show projecting nails, there is a considerable power of is not thefree movement (the hands being, in fact, used in manipulating the food), which

Fhoto by A. S. Rudland & Sons. DUGONG. A vegetable-feeding sea-mammal from the Indian Ocean and North Australian waters. 327

of the World328 The Living Animals

I'liolo by A. S. Rudland & Sons.

AMERICAN MANATEE.

Found in the Amazons River. The Matatees differ remarkably from the Dugorjg in the number and structure of their teeth.

is almost smooth, though there arecase in the limbs of the whale. The body of the dugong : that of the manatees is studded with short hairs. Thebristles in the region of the mouth : in neither sex of the manatees are such tusks developed.male dugong has two large tusks Finally, a more detailed examination of the skeletons would reveal the fact that, whereas the dugong has the usual seven bones in the neck, that of the manatees has only six.

When we come to the Whales, we shall encounter that very characteristic covering known it is present in smaller quantity, these sirenians have blubber asas " blubber "; and, though well. Complex stomachs they also have, like the whales, only in their case both the nature of the food and the structure of the teeth point clearly to a ruminating habit, which, for reasons that will be given in the right place, seems inadmissible in the whales. In both is furnished with singular horny plates, the precise use ofdugong and manatees the mouth which does not appear to have been satisfactorily determined; and the upper lip of the manatee is cleft in two hairy pads that work laterally. This enables the animal to draw all.the grass into its mouth without using the lower lip at

In their mode of life the dugong and manatees differ as widely almost as in their appearance; for the former is a creature of open coasts, whereas the manatees hug river-estuaries'? and even travel many miles up the rivers. Of both it has been said that they leave the water at night, and the manatees have even been accused of plundering crops near the banks. The few, however, which have been under observation in captivity have always been manifestly uncomfortable whenever, by accident or otherwise, the water of their tank was run off, so that there is not sufficient reason for believing this assertion.

This group of animals cannot be regarded as possessing any high commercial value, though both natives and white men eat their flesh, and the afore-mentioned rhytina was, in fact, exterminated solely for the sake of its meat. There is also a limited use for the bones as ivory, and the leather is employed on a small scale, a German writer has, in fact, been at great pains to prove that the Tabernacle, which was 300 cubits long, was roofed with dugong-fikin, and the Eed Sea is certainly well within the animal's range.

The Dugong, Manatees, Whales, Porpoises, and Dolphins 329

THE WHALES, PORPOISES, AND DOLPHINS.

Although anatomists have good reason for suspecting that all the members of the Whale Tribe are directly descended from river-dwelling forms, if not indeed, more remotely, from some land animal, there is something appropriate in the fact of the vast ocean, which covers something like three-quarters of the earth's surface, producing the mightiest creatures which have ever lived. There should also be some little satisfaction for ourselves in the thought that, their fish-like form notwithstanding, these enormous beings really belong to the highest, or mammalian, class of animal life.

One striking feature all these many-sized cetaceans have in common, and that is their similarity of form. Though they may vary in length from 70 to 7 feet, their outline shows a remarkable uniformity. Important internal and even external differences there may be. A whale may be toothed or toothless; a dolphin may be beaked or round-headed; either may be with or without a slight ridge on the back or a distinct dorsal fin; but no cetacean could well be mistaken for an animal of any other order. It is as well to appreciate as clearly as possible this close general resemblance between the largest whale and the smallest dolphin, it at its proper worth if weas the similarity is one of some interest; and we may estimate bear in mind that two species of cetaceans, outwardly alike, may not, perhaps, be more closely allied than such divergent ruminant types as the elephant, the giraffe, and the gazelle.

Reference has already been made to the fact that the whales are true mammals, and we must now clearly set before us the justification for separating them from the Fishes to which any one with a superficial knowledge of their habits and appearance would unhesitatingly assign them first separate them from theand raising them to the company of other mammals. Let us Fishes. The vast majority of fishes, with some familiar exceptions like the conger-eel, are covered with scales: whales have no scales. The tail of fishes, often forked like that of whales, is set vertically: in whales the tail is set laterally, and for this a good reason will presently be shown. Fishes have anal fins: whales not only have no anal fins, but their so-called pectoral : whales have fins differ radically from the fins of fishes. Fishes breathe with the aid of gills

Photo by A. S. Rudland & Sons. NARWHAL. An Arctic whale, with one or rarely two long spears of bone projecting from the head. 42

no gills. Fishes, in the vast majority of cases, reproduce their young by spawning, the eggs being left to hatch out either in gravel-beds or among the water-plants, lying on the bottom : whales (as in the case of the herring), or floating near the surface (as in that of the plaice) do not lay eggs, but bear the young alive. This brings us to the simple points of resemblance is born, it is nourished on its between them and other mammals. When the young whale mother's milk. This alone would constitute its claim to a place among the highest class. is peculiarly the covering of mammals, Whales breathe atmospheric air by means of lungs. Hair just as scales are characteristic of fishes and feathers of birds. Many whales, it is true, have no

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