THE CETACEA. 397 
zoonite is a very imperfect creature, but the joining of many together 
makes an animal which takes a somewhat high rank. Thus the 
division of labour in the animal economy may be classed under four 
heads :—1. Where many individuals are joined together to do the 
work of an association, as the corals and polypiers. 2. Where these 
individuals are in a yet closer union, as in the zoonites. 3. Where 
many instruments are concerned with the performance of the same 
functions. 4. Where special organs, single or double, are designed 
for special functions. 
The mammifers, or as they used to be called, the viviparous 
quadrupeds, are the vertebrates which most nearly approach man. 
Those members of the class which are inhabitants of the world of 
the sea form three classes, according to their construction and 
habits. 1. The mammifers having anterior members, which are 
transformed into fins, but are devoid of hind limbs—these are 
the cetacea. 2. Those which have all their limbs converted into 
flappers and fins, such are the sea Jions and the morses. 3. Those 
which possess members like ordinary quadrupeds, as the z/zée 
bears. The first two classes are the marine mammals proper ; the 
construction of the cetacea being the least complicated. 
The cetacea are essentially aquatic ; the greater number never 
leave the water ; but since they breathe by lungs they are compelled 
to rise to the surface to respire. The head of the cetacea is joined 
to the body by a neck so short and thick that there appears no 
contraction, but it seems as though the head grew out of the body. 
The trunk terminates in a thick, fleshy tail, which is horizontally 
flattened, not vertically, like the tails of fishes, so that the cetacea 
strike the water, not from right to left, but up and down. On the 
head the whales have a hole which communicates with the mouth : 
through this channel the animal ejects the air which it has inhaled ; 
and as it carries with it a large quantity of water, a fountain jet 
rises from the surface of the sea; the sailors then say the whales are 
“blowing.” The best divers are not able to remain under water 
more than a minute and a half, tut the cetacea can keep beneath 
the surface for some hours. The I’rench anatomist, Professor 
Breschet, discovered that the whales possessed a net-work of veins 
