The Structure of Game Fishes 9 
The brain of the fish is very small, and the lat- 
ter has limited intelligence. Its powers of smell 
are fairly well developed, and the hearing is more 
or less acute; the organs of hearing being small 
cavities on each side of the head, containing a 
liquid in which float two ear-stones or otoliths. 
In some fishes, as the California “groupers,” the 
stones are an inch in length, pearl tinted and 
flinty, — attractive objects in demand as “head- 
stones” and “good luck stones.” 
The fish is enveloped in scales, which in the 
game fishes described overlap each other like 
shingles. They grow out of the little pockets in 
the -skin and are moistened or lubricated by a 
secretion or slime, always noticed in a fish, which 
exudes beneath them, and particularly along the 
median line, an undulating line extending from 
the head to the base of the tail. The game fishes 
mentioned in this volume all increase by deposit- 
ing eggs or spawn, the eggs— minute spherical 
objects — often forming enormous masses. The 
caviare of commerce is the roe of the sturgeon. 
The number of eggs is inconceivable. In the cod 
it is estimated at five millions. This is a wise 
provision of nature, as fishes feed upon their own 
kind. Sardines, herrings, and many birds devour 
