Order IV. Cetacea. Cetaceans. 
The CETACEANS, abounding in all the seas of the Globe, and also 
even in some of the larger rivers of both Hemispheres, live entirely 
in the water, in which their young are brought forth; and they never 
appear upon the land unless accidentally thrown upon the beach by 
the waves. The Order contains the largest of living mammals, the 
Yellow-bellied Whale, B. suljurea, measuring ninety-five feet in length 
and weighing one hundred and forty-seven tons. Dependent upon air 
received into the lungs for respiration, whales are forced to rise at 
intervals to the surface, when the lungs are emptied with considerable 
force, causing a cloud of vapor to be lifted high in the air, which 
gives rise to the term “‘spouting”’ or “‘blowing,’’ and by this act the 
animal betrays its presence to the whaler. Admiurably adapted to a 
life in the water, these animals, although possessing a fish-like form, 
have an entire structure characteristic of the Mammalia. The 
Cetacea have two anterior limbs, and traces of a hinder pair. The 
forward pair is covered with a leathery skin, in shape like a flat- 
tened paddle, while the hinder limbs are not visible externally. 
Within the body there are indications of a pelvis, and two small 
bones that may represent the ischia. From want of use in the 
element in which they live, the hind limbs have become atrophied. 
The stomach, like that of the ruminants, is complex, and divided 
into several compartments, varying in number with the different 
genera, from three or four in PHoc#Na to eight in Zipuius, while 
the Sperm Whales have three, and the Whalebone Whales are stated 
to have four. These last, comprising the family BALANIDAE, are 
distinguished from the rest by the absence of teeth in both jaws, 
although, singularly enough, these are present in the early develop- 
ment of the embryo. The baleen, or so-called ‘“‘whalebone,”’ is a 
series of flattened horny plates (varying in number, amounting in 
some cases to as many as four hundred), which are placed on each 
side of the palate, leaving an open middle space. They serve as 
strainers, being in close proximity, and retain the small molluscs, 
fish and other creatures, when the water that has been taken with 
them into the mouth is ejected. The color of the baleen varies from 
jet black through different shades to creamy white. Baleen Whales 
are distinguished by their enormous heads, which are about one- 
third the total length of the animal, a curved mouth extending 
behind the blow-holes, apparently pigmy eyes (although they are 
four times the size of those of an ox); short heavy pectoral fins, and 
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