THE SHORES OF BRITAIN. 81 
ship, worthy, of the Divine hand that formed it, 
The scales of some fishes are so minute as to be 
with difficulty distinguishable; such as those of the 
Kel: to procure these for microscopical examination, 
“take a piece of the skin of the Eel that grows on 
the side, and while it is moist spread it on a piece 
of glass, that it may dry very smooth; when thus 
dried, the surface will appear all over dimpled or 
pitted by the scales, which lie under a sort of cuticle, 
or thin skin: this skin may be raised with the sharp 
point of a penknife, together with the scales, which 
will then easily slip out, and thus you may procure 
as many as you please.”* 
The limbs of fishes differ greatly in appearance 
from those of terrestrial animals; consisting, as to 
the portion external to the body, of slender spines, 
sometimes cartilaginous and jointed, at others bony 
and simple, united by means of a thin membrane. 
stretched from one to the other. Generally there 
are two pairs on the under part of the body, which 
are called the pectoral and the ventral fins, and re- 
present respectively the fore and hind legs of qua- 
drupeds, or the wings and feet of a bird. Besides 
these, there are one or more perpendicular fins along 
the back, called the dorsal, and one below the body, 
near the tail, called the anal; but the main instru- 
ment of motion is the broad, perpendicdlar fin, which 
terminates the body, often called the tail, but, more 
correctly, the caudal or tail fin. To rightly under- 
stand the motions of a fish, we must bear in mind 
that it is immersed in a fluid which is of little less 
* Martin’s Micrographia Nova, p. 29. 
6 
