SWIFTNESS OF FISHES. 187 
If the whole economy of the world of fishes were opened to 
our view, the magnificent picture would, no doubt, give us ad- 
ditional reasons for admiring the infinite wisdom of the Creator ; 
but the little we do know suffices to convince us that the 
same wonderful harmony existing between the anatomical 
structure and the outward relations or mode of life in birds and 
mammiferous quadrupeds is also to be found in fishes, and that 
these creatures, though occupying a lower grade in Creation, are 
no less beautifully adapted to the peculiar element in which 
they are destined to live and move, 
This strikes us at once in their external form, which, though 
subject to great variety, being sometimes spherical as in the 
globe-fish, or cubical as in the ostracion, or expanded as in the 
skate, or snake-like as in the eel, is generally that of an elon- 
gated oval, slightly compressed laterally, a shape which enables 
the fishes to traverse their native fluid with the greatest celerity 
and ease. We wisely endeavour to imitate this peculiar form 
in the construction of our ships, yet the rapidity with which the 
fastest clipper cleaves the waters is nothing to the velocity of an 
animal formed to reside in that element. The flight of an 
arrow is not more rapid than the darting of a tunny, a salmon, 
or a gilt-head through the water. It has been calculated that a 
‘salmon will glide over 86,400 feet in an hour, that it will 
advance more than a degree of the meridian of the earth in a 
day, and that it could easily make the tour of the world in some 
weeks, were it desirous of emulating the fame of a Cook or of 
a Magellan. Every part of the body seems exerted in this 
despatch ; the fins, the tail, and the motion of the whole back- 
bone assist progression; and it is to this admirable flexibility of 
body, which mocks the efforts of art, that fishes owe the 
astonishing rapidity of their movements. 
Whales and dolphins move onwards by striking the water 
in a vertical direction, while fishes glide along by laterally 
curving and extending the spine. In some species, such as the 
eel, the whole body is flexible; but most of them paddle ay ay 
with their tail to the right and left, and are thus driven forwards 
by the resistance of the water. Consequently the power of 
fishes is chiefly concentrated in the muscles bending the spine 
sideways, and generally we find these parts so much developed 
as to form the greatest part of the body. 
