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114 broad abrupt muzzle. Both sides of the upper jaw are furnished with transverse plates of a horny substance, called baleen; the lower jaw is destitute of teeth. The number of species belonging to this family is very limited; they are comprised in two genera, Balena and Balenoptera, of which the latter attains the largest size, but the former is the most valuable to man, on account of its yielding, in greater abundance, the important products of oil and baleen, or whalebone. The Arctic and Antarctic seas are the principal, but not exclusive resorts of these immense creatures.

The Whalebone-whale is distinguished as a genus by the total absence of a dorsal fin; by the plates of baleen being large and numerous, and by the skin of the under parts being destitute of folds.

The most valuable species is that of the Arctic Ocean, known as the Greenland Whale, or as the "right whale" of seamen (Balena mysticetus, .). It attains a length of fifty or sixty feet, and a thickness of ten or twelve. The form is clumsy, though in a less degree than that of the Cachalot, the head being large, and the mouth enormous; the gullet, however, is not sufficiently capacious to admit the passage of a man’s hand. Its food consists exclusively of minute animals that swarm in its native seas, some of which are small crustacea, others medusæ and mollusca. The food is received in a singular manner. The branches of the lower jaw are slender, and widely arched outwardly, so as to form the frame of an