How many species of these monstrous creatures exist in the ocean we cannot tell, seeing that the observations of the Whale-fishermen are generally by no means sufficiently precise for the purposes of Natural History. That which appears to be most frequently met with is the Great-headed Spermaceti Whale. This giant of the deep has merely a callous hump upon its back, in place of a dorsal fin. On each side of its lower jaw are from twenty to twenty-three large conical teeth. The “blow hole” through which it respires is a single orifice, situated on the top of the head—not a double aperture as in most other Cetaceans. The species seems to be widely distributed, but its range is principally confined to the oceans south of the Equator. THE WHALEBONE WHALES. These Whales resemble the Cachalots, both in the vastness of their bulk, and in the disproportionate size of their head, when compared with their entire length. Their forehead, however, is considerably flatter than that of the Spermaceti Whales, and they have no true teeth. Instead of the usual implements of mastication, their upper jaw, which somewhat resembles a great boat turned keel upwards, or the roof of a house, has its under surface densely furnished with plates of a substance called “whalebone,” consisting of horny plates resembling the blades of scythes, placed transversely. These becoming thinner towards their edges, are fringed with a long hair-like border, so that the whole apparatus forms an immense sieve. The Whalebone Whale—long considered as the largest animal at present in existence—according to the testimony of the Rev. Captain Scoresby, seems rarely, if ever, to exceed seventy feet in length; a size, which, although prodigious, is exceeded by some other Cetaceans. Its back is unprovided with a dorsal fin. The blubber, or elastic fat beneath its skin, which is sometimes several feet in thickness, furnishes immense quantities of oil, in search of which whole fleets were formerly fitted out, until the entire race of these Whales has become almost extinct. At a very recent period these leviathans of the ocean were not uncommonly met with on the British coast; but generally they have been compelled to retire for safety to the recesses of the ice-bound coasts of the north, and even there they are rarely to be encountered, their number appearing to constantly diminish.