WHALES AND DOLPHINS. 
85 
represented by a pair of elongated slender bones, suspended 
below, and at some distance from, the vertebral column, in the 
reo-ion of the loins. Since these bones are concealed in the 
o 
flesh and not connected with the spinal column, they are often 
lost in preparing skeletons. To the outer side of these, in some 
Whales, are attached small bones which represent the bones of 
the limb. In the skeleton of the Common Rorqual [Balceno- 
ftera rnusculus) a little nodule of bone, scarcely larger than a 
walnut, has been preserved ; it is the rudiment of the thigh- 
bone or femur, and the only trace of a hind-limb which this 
gigantic animal possesses. The existence of these rudimentary 
structures has an important bearing upon the origin and past 
history of IVhales and their relationship to other Mammals. 
Cetaceans abound in all seas, and some species are inha- 
bitants of the larger rivers of South America and Asia. Their 
organization necessitates passing their life entirely in the water, 
as on land they are absolutely helpless. They have, however, 
to rise frequently to the surface in order to breathe ; and, in 
relation to the constant upward and downward movement in the 
water thus necessitated, their principal instrument of motion, 
the tail, is expanded horizontally, unlike that of a Fish, in which 
the movements are mainly in straightforward or lateral directions. 
The position of the nostrils on the highest part of the head is 
important for this mode of life, as it is the only part of the 
])ody the exposure of which above the surface is absolutely 
necessary. The “ spouting,” or properly blowing,” of Whales 
is nothing more than the ordinary act of breathing, performed 
at longer intervals than is the case with land-animals. The 
moment a Whale rises to the surface it forcibly expels from 
its lungs the air taken in at the last inspiration, which of 
course is heated and charged with water-vapour. This, rapidly 
condensing in the cold atmosphere in which the phenomenon 
is often observed, forms a column of steam or spray, which has 
been mistaken for water. Frequently, however, it happens, 
especially when the surface of the ocean is agitated into waves, 
that the animal commences to “ blow before the nostril has 
cleared the top of the water, some of which may thus be 
driven upwards with the blast. In hunting Whales the 
