50 CETACEANS. 
to seventeen in the upper, and from twelve to fifteen in the lower jaw. In 
form the teeth are conical and pointed, and they are set close together; those in the 
front of the jaws of old animals being directed outwards. The back-fin is small 
and hook-like, while the flippers are of moderate size, broad at the base, and 
subovate in form. These dolphins attain a length of from 7 to 74 feet, and are of 
a slaty or blackish colour. In the Irawadi dolphin the colour is pale slaty above 
and whitish below, with numerous irregular streaks on the sides; but in the one 
inhabiting the Bay of Bengal the colour is uniformly blackish without any streaks. 
The latter form, whether it be specifically distinct from the dolphin of the Irawadi, 
or merely a variety, appears never to ascend the rivers beyond the distance 
influenced by the tides, while the Irawadi dolphin never descends to the estuaries. 
The following account of the habits of the Irawadi dolphin is 
taken from Dr. J. Anderson, who writes that it “has much the 
character of its marine fellows, being generally seen in small schools, which 
frequently accompany the river steamers, careering in front and alongside of them, 
as is the custom of the dolphins of the sea. Occasionally, however, a solitary 
individual may be observed, but this is the exception, as two or three are usually 
associated together, hence this may be considered as a gregarious form. In the 
defile below Bhamo, where the river runs for ten miles over a deep bed forty 
to sixty fathoms in depth, and from two hundred to five hundred yards in width, 
and defined by high, wooded hills on either side, numerous troops of dolphins may 
be observed passing up and down, rising every minute or two to the surface to 
emit the short blowing sound, which ends in the more feeble one of inspiration, 
and all night through this sound may be heard. They never leave the deep water ; 
and when they rise to breathe (which they do in periods varying from sixty to 
one hundred and seventy seconds, although occasionally exceeded) the blowhole is 
first seen, then at the end of the inspiration the head disappears and the back 
comes into view, and is gradually exposed as far as the dorsal fin, but the tail- 
flippers are rarely visible. The act of breathing is rapid, so much so indeed 
that it requires a very expert marksman to take aim and fire before the animal 
disappears. 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 fully exposed, when they ejected great volumes of water out of their 
mouths, generally straight before them, but sometimes nearly vertically ... 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 
attitude, 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.” The food of this dolphin apparently consists exclusively of fish. 
Dr. Anderson adds that “the fishermen believe that the dolphin purposely draws 
fish to their nets, and each fishing-village has its particular guardian dolphin, 
which receives a name common to all fellows of his school; and it is this superstition 
which makes it so difficult to obtain specimens of this Cetacean.” 
Habits. 
