[DENTICETE—THE TOOTHED WHALES.]
None of the larger species are found on these coasts, or in the Indian Ocean, the two most interesting of which are the gigantic sperm whales (Physeter macrocephalus), and the curious narwhal or sea unicorn (Monodon monoceros). The latter is an inhabitant of the northern seas only, but the sperm abounds in warmer waters, being frequently found in the sub-tropical oceans. I have occasionally seen them in the South Atlantic, though they are said to have diminished there of late years. It is a wonder that the species does not get scarce in many localities, so great is the chase after them. During the last forty years the Americans alone have taken at the rate of 10,000 barrels of sperm oil per annum, or upwards of four million barrels since 1835. The sperm whale, though of such enormous bulk and courage, yet has enemies besides man. The thrasher and the killer whale both attack it, and sailors assert that the sword-fish and thrasher combine against it, the latter stabbing from below, whilst the former leaps on it with stunning blows. I think by sword-fish (Xiphias), which is also a large but not so very sanguinary a fish, they mean the saw-fish (Pristis), which is allied to the sharks, and which attacks the largest whales. The sword-fish has however the character of being pugnacious. The old sperms, especially males, will show fight at times, but the younger ones are easily alarmed, and on being molested rush off in various directions, each looking out for himself. The sperm whale is known from the others by the way in which it spouts, the jet being thrown up obliquely forwards, and it blows at regular intervals. Although the old "bulls" show a certain amount of ferocity at times, their savageness is considerably exaggerated by the whalers, who love to spin yarns about them. Having watched the habits of these and the baleen whales with curiosity, I tried to get as much information about them as I could, from the whalers, but, with the exception of the officers of whaling ships, there was much that was unreliable in Jack's notions about the sperm. On one occasion I was just too late to see one killed. The boats, under full sail, were towing the carcase towards the ship. I would have given a good deal to have seen the encounter. The food of the sperm consists greatly of the huge rock squid or cuttle-fish, which they swallow in large lumps. I have heard whalers assert that a wounded sperm in the death agony will vomit immense pieces of squid. In this respect it differs much from the baleen whales, which have a narrow gullet. According to Professor Flower there is no sufficient evidence of the existence of more than one species of sperm whales, but an allied species, Physeter (Euphysetes) simus, is found on the Madras coast, and to this I will allude further on.
[FAMILY DELPHINIDÆ—THE DOLPHINS OR PORPOISES.]
[GENUS PLATANISTA—THE RIVER DOLPHINS.]
A globular head with a long, compressed and, towards the end, spoon-shaped rostrum or snout; flippers short, broad and triangular; a long body of moderate girth; no back fin, but a slight elevation which takes its place. There is a decided depression between the head and body on the region of the neck; the eye is remarkably small, so much so as to be hardly perceptible; in an adult of eight feet long the whole eye-ball is no bigger than a pea, and the orifice of the ear is like a pin-hole.
The skull has peculiar features. "The apparently rounded skull behind the snout has broad, thick zygomatic arches, and above and in front of these the cheek-bones (maxillæ) each send forwards and inwards a great roughened sheet of bone or crest, which forms a kind of open helmet. In the large hollow between these bony plates, and somewhat behind, are situated the nasal orifices, which are slightly awry" (Murie).[19] Professor Flower's notice of the skull ('Osteology of the Mammalia') is thus worded: "The orbit is extremely small, the temporal fossa large, and the zygomatic processes of the squamosal are greatly developed. From the outer edge of the ascending plates of the maxillæ, which lie over the frontals, great crests of bone, smooth externally, but reticulated and laminated on their inner surface, rise upwards, and, curving inwards, nearly meet in the middle line above the upper part of the face."
19 See [Appendix B] for illustration.
The dentition is also curious, the upper and lower jaws being provided with a number of teeth, pointed and conical in front, and smaller and more flattened behind. They vary in number. In an example quoted by Dr. Murie the total was 117, viz., 27—28/30—32, but in a specimen examined by Dr. Anderson, who has most exhaustively described these animals, the total number of teeth amounted to 128, i.e. 33—32/32—31. (See [Appendix B].)
The cervical vertebræ are movable, and not ankylosed, as in many of the cetacea; the cæcum is small; the blow-hole is a narrow slit, not transverse as in other whales, but longitudinal. I have somewhat gone out of order in Jerdon's numbering in bringing in this genus here instead of letting it follow Delphinus, as he has done. These river Dolphins naturally come after the extinct Phocodontia or seal-toothed whales, and bear considerable resemblance in the dentition to the extinct genus Squalodon.
[NO. 257. PLATANISTA GANGETICA.]
The Gangetic Porpoise (Jerdon's Nos. 144 and 145).