Most writers have asserted that swine are long-lived, but few instances are allowed to occur of their attaining a great age; as it is neither profitable nor convenient to keep them to the full extent of their time. A gentleman in Hampshire kept a sow till she was nearly seventeen years old; and, at this period, she began to exhibit some signs of old age by the decay of her teeth, and ceasing to be so fertile as she had previously been. This animal afforded an instance of the extremely prolific nature of swine. She is calculated to have been the parent of no fewer than 300 young ones. The great weight to which swine are sometimes fed would appear altogether incredible had it not been well attested. In one instance a pig was known to weigh 1410 pounds when alive; and 1215 pounds when killed and dressed. ORDER VII.--CETE, OR CETACEOUS ANIMALS. 117. _The NARWAL, or SEA-UNICORN_ (Monodon monoceros) _is a marine animal from twenty to thirty feet in length, with a long, tapering, twisted, and pointed weapon of ivory in front of the head._ _It has a small fin on each side of the breast, in place of fore feet, an horizontally flattened tail, and a spiracle or breathing hole on the highest part of the head. The skin is white, variegated with numerous black spots on the upper parts of the body; and the weapon is generally from five to eight feet in length._ _These animals are found in the Greenland seas, and they occasionally migrate southward off the British coasts. Their name of_ narh-wal _signifies a whale that subsists on dead bodies._ The Greenlanders pursue the narwals as they do other whales, chiefly on account of the _oil_ which they obtain from them. This is considered superior, in many respects, to the oil of the great whale (118), and is used by them both with food and to burn in their lamps. These people also eat the _flesh_ of the narwal prepared by fire, dried in a half putrid state, and sometimes even raw; and they are also partial to the _intestines_ as food. The _tendons_ serve them as a strong kind of thread. The projecting _weapon_, which is not a horn but a species of tusk, in its substance not much unlike the tusk of an elephant, is sometimes cut into the heads of arrows; and, in some parts of Greenland where wood is scarce, these weapons are occasionally used in the structure of tents and sledges. As ivory, they are not of much use, since, from their twisted form, they cut to great disadvantage. The kings of Denmark have, in the castle of Rosenberg, a throne formed of the tusks of the narwal.