8 Guide to Whales, Porpotses, and Dolphins. 
In most members of the order, but more especially in the true 
Whales, the head is large in proportion to the body, attaining in 
some species of the latter more than one-third the entire length of 
the animal; and the mouth is always wide, and bounded by stiff 
immobile lips. The fore-limbs are reduced to the condition of 
flattened flippers, or paddles, encased in skin, showing no 
external sign of division into arm, fore-arm, hand, or separate 
fingers, and without any trace of nails. No signs of hind-limbs 
are externally visible. The general surface of the skin is smooth, 
glistening, and devoid of hair, although in most species there are 
a few fine bristles in the neighbourhood of the mouth, which 
may either remain throughout life, or are found only in the young 
state. Certain other species, notably the Indian Porpoise, have 
minute scales embedded in the skin of part of the back; and 
these suggest that Whales are derived from animals furnished 
with a complete bony armour. Immediately beneath the skin 
is a thick layer of fat, held together by a mesh of fibrous tissue, 
constituting the ‘“ blubber,”’ which serves the purpose of the 
hairy coat of other Mammals in retaining the heat of the body. 
In most species there is a fin, more or less triangular in shape and 
composed only of skin and fibrous tissue, situated near the middle 
of the back, which may aid in maintaining the position of the 
animal in the water. The eye is small; and the aperture of 
the ear minute, and without any vestige of a conch. The 
nostrils, or ‘ blow-holes,” open separately, or by a single valve- 
like aperture, placed (except in the Sperm-Whale) near the top of 
the head. 
The bones are generally spongy in texture, their cavities being 
filled with oil. In the back-bone the region of the neck is 
remarkably short and incapable of motion, and the vertebra, 
seven in number, as in other Mammals, are in many species more 
or less completely fused into a solid mass. None of the hinder 
vertebre of the body are united together to form a “ sacrum,” 
or to join the pelvis. The vertebra of the loins and tail are 
numerous, large, and capable of free motion; and very frequently 
vary in number in different individuals of the same species. 
Beneath the latter are large V-shaped ‘ chevron-bones’”’ which 
project downwards, and give increased surface for the attachment 
of the muscles which move the tail; but there are no bones 
supporting the lateral “ flukes” of the tail or the back-fin. It has 
been suggested that the flukes are formed in part by remnants 
