The animals are gregarious and usually travel in herds of five to ten individuals; more than ten are rare, but many different schools may be in sight at the same time, separated from each other by only a short distance. The old bulls sometimes lead a solitary life, but herds of young bulls, cows, and calves, led by a bull, are often seen. The differences of age and sex can easily be determined both by the color and the shape of the head. The young vary from black to light brown in the older individuals and females, and old bulls are often almost yellow, with much white about the head and neck. The mating period appears to be in April or May and the period of gestation about twelve months, although there is little definite information concerning breeding habits. Like all cetaceans, the young are very large at birth, and Captain Gray writes that from a female bottlenose twenty-nine feet long he removed a fœtus ten feet in length by five feet six inches in circumference. A fœtus of slightly larger size has also been recorded by Guldberg. The hearing of the bottlenose is very acute and a school of whales will detect the sound of a ship’s propeller at a long distance, but instead of being frightened, the animals often surround the ship or boats and exhibit the greatest curiosity; nor will they leave until they have thoroughly examined the strange object. A herd will never leave a wounded comrade while it is still alive, but swim away as soon as it is dead. The hunters often take advantage of this loyalty, after they are fast to a bottlenose, by harpooning a second before the first is killed. The whales crowd about the wounded ones, coming in the most mysterious manner from all parts of the compass, and sometimes ten or fifteen can be taken before the school is lost. The bottlenose appears to feed exclusively upon a bluish-white cuttlefish about six inches long, for nothing else has been taken from their stomachs as far as I have been able to learn. Like the orca and sperm whale, when a bottlenose is killed it almost always ejects large quantities of cuttlefish from its mouth. Judging by the length of time the animals remain under water and their heavy spouts when reappearing, they must have to go to a great depth to find their food. The two minute teeth at the tip of the lower jaw can be of no assistance whatever in feeding and will undoubtedly eventually disappear altogether. The bottlenose is common in the North Atlantic and Arctic Oceans, and although rare on the Finmark coast are numerous about Spitzbergen, Iceland, Nova Zembla, East and West Greenland, Davis Straits, and Labrador. Near the Faroe Islands and Iceland they have been most relentlessly persecuted and hundreds of whales are taken annually.