THE INIA, OR AMAZON DOLPHIN,[232] is another of the remarkable fresh-water forms. The former name is that given to it by the Indian tribes of Bolivia. It ranges from the mouth of the river up the whole of its affluents of any magnitude, 2,000 miles from the sea. Mr. Bates, in his “Journey on the Amazon,” tells us that when it rises the top of the head is the part first seen; it then blows and immediately afterwards dips head downwards, its back curving over, exposing successively the whole dorsal ridge with its fin. It seems thus to pitch heels over head, but does not show the tail fin. It generally goes in pairs. Exceedingly numerous throughout the Amazons, it is nowhere more plentiful than in the shoaly water at the mouth of the Tocantins, especially in the dry season. The Indians have a story that the “Bouto,” as they also call this creature, “once had the habit of assuming the shape of a beautiful woman, with hair hanging loose to her heels, and walking ashore at nights in the streets of Ega, to entice the young men down to the water. If any one was so much smitten as to follow her to the water-side, she grasped her victim round the waist and plunged beneath the waves with a triumphant cry.” It is held in veneration, and on this account the Indians can hardly be induced to harpoon it. They have a superstition that blindness results from the use of its oil (which nevertheless is excellent for lamps), and though Mr. Bates prevailed upon an Indian to capture one, the fellow repented of his deed the day afterwards, declaring that his luck had there and then forsaken him. This animal is seven or eight feet long. Its colour commonly is bluish above, passing into a pale flesh-colour beneath, the tail and flippers being bluish, but the tints vary considerably, and even differ with age and season. The head is furnished with a long beak. There is a kind of keel-shaped dorsal fin, and the flippers are of fair size, broadish and tapering, thus differing from those of the Susu. The skull has a certain resemblance to that of the Gangetic Dolphin, but without the great cheek-crests peculiar to the latter, besides other minor differences. In both jaws there is a long series of stout conical teeth of a pretty uniform size. These vary in number in different specimens, as the following formulæ in two separate individuals show 26–26 25–27 = 104; 34–32 33–32 = 131. The muzzle of the young is hairy; while both the eye and the ear-hole are much better marked than in the Susu. It is a fish-eater, and the mother exhibits great affection and devotedness towards her young.
THE PONTOPORIA.[233]—Like Inia this is a South American form, and is now known to inhabit the mouth of the La Plata and other rivers entering into the Atlantic on the coasts of the Argentine Republic and Patagonia. But, unlike the two preceding forms, it is not confined to the rivers, for it ranges along the sea-coast. The very few specimens met with show it to be a small animal, not more than four feet long, of a blackish tint, pale beneath, with a white streak along each side from behind the blow-hole. It has an unusually long narrow beak, but not such a prominent head as in the two others. This animal has a well-marked triangular dorsal fin, and the fore-flipper is somewhat fan-shaped and broadish, and not pointed as in the Inia. The crestless skull has characters intermediate between the river Dolphins and the marine Dolphins to be described farther on. The teeth are small and very numerous, somewhat fewer in the young animal, conical in shape, with a swollen ring round their base. The dental formula is as follows:— 53–53 53–53 = 212 or 57–57 54–54 = 222.
THE ZIPHIOID WHALES (ZIPHIIDÆ).
These singular Whales form a very compact group, closely united by common attributes, but they are readily separated by definite characters from others. Until the beginning of the present century, the Bottlehead (or Butzkopf) was that only known. Since then, at irregular intervals, chiefly solitary individuals have been caught or stranded in various parts of the world; but even now the numbers coming under observation have been few. Their apparent comparative rarity in the present day is in great contrast with the frequent discovery of their remains in the Norfolk Crag formations, where fragments, principally of their dense solid beaks, show that they must have been at a long distant period exceedingly numerous. On these grounds the supposition has been expressed that the present paucity of forms is indicative of a survival of an ancient family that once played an important part in Nature. The living forms range from fifteen to thirty feet in length, but their ocean habits are extremely obscure. Their common characters are long narrow beaks, elevated heads, a small but well-marked dorsal fin placed behind the middle of the back, short flippers with rounded extremity, a pair of short throat-furrows of a V-shape (point in front), a single somewhat crescentic blow-hole, placed crosswise in the middle of the head, absence or only rudiments of teeth in the upper jaws, and one or two pairs of very peculiar teeth, variable in size, in the lower jaws, along with certain other peculiarities of the skull. We shall refer but to a few of the group.
Of the genus Ziphius we may admit CUVIER’S WHALE [234] and VAN BENEDEN’S WHALE.[235] Their size appears to vary from sixteen to twenty-four feet, and their colour is said to be steel-grey, with irregular white body streaks, the abdomen also being whitish. The head is less prominent than in the Bottlehead, and the snout is a trifle shorter, with the lower jaw slightly upturned, fuller than the upper, and furnished with two teeth at the tip. The flippers are short and somewhat pointed, and the dorsal fin is situated well behind, and not very large. There is a deep hollow at the base of the rostrum or beak, over which the skull rises crest-like from behind forwards. The genus Ziphius was originally based on a supposed fossil skull from near the mouth of the Rhone; living species, however, have been since recorded, and of one from South America Burmeister gives a detailed notice under the name of Epiodon australis; still it is doubtful whether this is not one of the two above-mentioned animals.
HEAD OF MESOPLODON. (After Andrews.)
SOWERBY’S WHALE[236] is representative of the genus Mesoplodon. This animal is black above, white below, and the sides marked with wriggly white streaks. The small dorsal fin is situated well back, the flippers are small and narrow, the head is rather low, sloping towards the beak, and the upper jaw is shorter than the under. It also has two teeth in the lower, and none in the upper jaw. Thus externally it bears strong resemblance to Cuvier’s Whale, but it differs in the slender beak, without a hollow at its base. Sowerby’s Whale is interesting from having been first obtained in 1800 off the Elgin Coast, and described by Mr. Sowerby as the Two-toothed Cachalot (Physeter bidens). The genus Mesoplodon has since given rise to considerable discussion, various names being assigned to it. Professor Flower points out that of the various Ziphioid Whales obtained on British coasts, France, the Cape, and New Zealand, described as different genera, &c., he recognises seven species of Mesoplodon, Sowerby’s Whale being the type, and the others differing chiefly in the form of the teeth. Another of this curious family is the NEW ZEALAND BERARDIUS,[237] of which some four specimens only are known to science. Dr. Julius Haast records the capture of one near Canterbury, New Zealand, in 1868, which animal was 30½ feet long, velvety black, with greyish belly. One of the observers who saw the creature alive stated that it protruded its teeth—a remarkable fact if true. In its stomach were found half a bushel of the horny beaks of a species of Octopus. Professor Flower has described its skeleton, and affirms that it is truly ziphioid in character, but on the whole approaches nearer to the true Dolphins; whereas the Bottlehead is modified in the direction of the Sperm Whales. THE BOTTLEHEAD, OR COMMON BEAKED WHALE,[238] is a constant visitor to the coasts of Britain, many instances having been recorded of its capture, and one classical example came under the scalpel of the celebrated anatomist John Hunter. It inhabits the breadth of the North Atlantic, and according to Eschricht very probably spends the summer far north in the Polar Sea, and migrates southwards towards autumn or winter. Dr. R. Brown regards it as rare in the Greenland Seas, three or four, however, being occasionally seen at the mouth of Davis Strait. On the French and Scandinavian coasts small herds have sometimes run ashore. The female gives birth to a single young one in autumn. They feed chiefly on cuttle-fish, but also upon soft-bodied Trepangs (Holothuria). It ranges from twenty to forty feet in length, according to age and sex, and is of a uniform blackish hue, lighter beneath, but not white. The skull is most peculiar in having two crests at the occiput, of most unequal size and figure, and the cheek-bones at the root of the beak raised into a pair of huge elevations. The upper jaw is toothless, and the lower jaw has only two or three small concealed teeth. The neck vertebræ are united; and moreover the stomach is remarkable even among Cetacea for the number of chambers it contains, there being some six or seven divisions.