Part 47 (2/2)

Dr. Anderson, who has fully described this species, says that he has ”never observed it in tidal waters, so that it is even more strictly fluviatile than the Gangetic dolphin. From a little below Prome to as far up as Bhamo, which is about 550 miles, as the crow flies, from the sea, these animals abound. It is a.s.serted by the Shans of Upper Burmah that these dolphins are not to be found beyond a point thirty miles above Bhamo, where the course of the river is interrupted by rocks, and which they style _Labine_ or Dolphin Point, from the circ.u.mstance that, according to them, it is the residence of certain _Nats_, who there impose so heavy a toll on dolphins as to deter them from proceeding upwards.”

This dolphin is somewhat like its marine cousins, being fond of gambolling round the river steamers. Solitary ones are seldom met with, usually two or three being together. When they rise to breathe the blow-hole is first seen; then, after respiration, the head goes down, and the back as far as the dorsal fin is seen, but rarely the tail flippers. They rise to breathe every 70 to 150 seconds, and the respiratory act is so rapid that it requires a very expert marksman to take aim and fire before the animal disappears.

Dr. Anderson says: ”I have observed some of them disporting themselves in a way that has never yet been recorded of _Cetacea_, as far as I am aware. They swam with a rolling motion near the surface, with their heads half out of the water, and every now and then nearly fully exposed, when they ejected great volumes of water out of their mouths--generally straight before them; but sometimes nearly vertically. The sight of this curious habit at once recalled to me an incident in my voyage up the river, when I had been quite baffled to explain an exactly similar appearance seen at a distance, so that this remarkable habit would appear to be not uncommonly manifested.

On one occasion I noticed an individual standing upright in the water, so much so that one-half of its pectoral fins was exposed, producing the appearance against the background as if the animal was supported on its flippers. It suddenly disappeared, and again, a little in advance of its former position, it bobbed up in the same att.i.tude, and this it frequently repeated. The Shan boatmen who were with me seemed to connect these curious movements with the season--spring--in which the dolphins breed.”

A similar thing has been noticed in the case of marine dolphins off the coast of Ceylon by Mr. E. W. H. Holdsworth, whose observations confirm the opinion of the Shan boatmen. (See 'P. Z. S.' 1872, p.

586.)

”The food of the Irrawady dolphin is apparently exclusively fish.

The fishermen believe that the dolphin purposely draws fish to their nets, and each fis.h.i.+ng village has its particular guardian dolphin, which receives a name common to all the fellows of his school, and it is this supposition that makes it so difficult to obtain specimens of this cetacean. Colonel Sladen has told me that suits are not unfrequently brought into the native courts to recover a share in the capture of fish in which a plaintiff's dolphin has been held to have filled the nets of a rival fisherman” (_Anderson_). This reminds me that in the surveying voyage of the _Herald_, as related by Mr.

H. Lee, the natives of Moreton Bay entreated the seamen not to shoot their tame porpoises, which helped them in their fis.h.i.+ng.

_GENUS DELPHINUS--THE MARINE DOLPHINS_.

These are characterised by a convex forehead, with a protruding muzzle which forms a sort of beak; they have teeth in both jaws, numerous and conical, broad and high cranium, nasal pa.s.sages vertical, no caec.u.m. They are gregarious in habit, carnivorous and extremely swift, but they must not be confounded with the dolphin of sailors, which is a true fish (_Coryphaena hipparis_) of great velocity and brilliant colours, which change like rainbow tints when the fish is dying. I have several times in vain tried to catch the fleeting shades with both oil and water-colours, but without success; for within a few minutes they change from the most vivid of greens and blues to a pale silvery grey. The true dolphin, of which we are treating, is the dolphin of the ancients, represented in all the old pictures and sculptures. They have a medium dorsal fin, and the pectoral flippers are about two-thirds longer than the breadth.

[Ill.u.s.tration: 1. Gangetic Dolphin--_Platanista Gangetica_. 2.

Round-headed River Dolphin--_Orcella brevirostris_. 3. Gadamu Dolphin--_Delphinus Gadamu_. 4. Freckled Dolphin--_Delphinus lentiginosus_. 5. Black Dolphin--_Delphinus pomeegra_.]

NO. 260. DELPHINUS PERNIGER.

_The Black Dolphin_ (_Jerdon's No. 142_).

HABITAT.--Bay of Bengal.

DESCRIPTION.--”Twenty-six teeth on each side above and below, obtuse, slightly curved inwards; of a uniform s.h.i.+ning black above, beneath blackish.”--_Jerdon_.

SIZE.--Total length, 5 feet 4 inches.

This species was taken in the Bay of Bengal and sent to the Asiatic Society's Museum by Sir Walter Elliot, but it does not appear to be mentioned by Professor Owen in his notice of the Indian Cetacea collected by Sir Walter Elliot.

NO. 261. DELPHINUS PLUMBEUS.

_The Lead-coloured Dolphin_ (_Jerdon's No. 143_).

HABITAT.--Malabar coast.

DESCRIPTION.--Thirty-six teeth in each side in the upper jaw and thirty-two in the lower jaw; of a uniform leaden colour, with the lower jaw white.

SIZE.--About 8 feet.

Whether this be the same as or a different species to the next I am unable to say, as the description is meagre, and the number of teeth vary so much in the same species that no definite rule can be laid down on them.

The following are the species named by Professor Owen and collected by Sir Walter Elliot.

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