NATURAL HISTORY. 
51 
ROOM XI.] 
Siluri, an adipose, hinder dorsal fin, but the body is 
covered with regular scales. They principally ascend 
rivers to spawn. They are voracious, and prey on insects 
and small animals. This family has been divided into 
several genera, according to the form and presence of the 
teeth, and the position of the fins. 
Cases 5 and 6. The Herrings (Clupeidce) have a 
scaly body like the Salmons, but no adipose dorsal fin, and 
their upper jaw is formed in the middle b}^ the inter¬ 
maxillary, and on the sides by the maxillary bones. 
With the Herrings are placed the Bony Pike ( Lepisos - 
tens), which has many of the characters of the Pike, with 
the structure of the head of the Herring. The body is 
covered with a case formed of very hard square scales, and 
the two outer rays of the tail and of the other fins, are 
fringed with similar scales. They live in the warm parts 
of South America, and afford good food. 
The second division of this order contains those fishes 
whose ventral fins lie immediately under the pectorals. 
It contains three families, distinguished by the shape of 
the body. 
The Cod-Fish ( Gadidce) have a lance-shaped body, 
covered with small scales. The head is without scales, 
and the back has generally two or three dorsal fins ; 
the ventral fins are always slender. They generally live 
in the seas of cold and temperate climates, and by their 
abundance are important as objects of commerce. They 
are divided into several genera, according to the number 
of the fins. The true Cod (. Morrhuo ) has three dorsal 
fins and a small beard; the Coal-Fish ( Merlangus ) has also 
three dorsal fins, but no beard ; while the Stock-Fish 
( Merluccias ) has only two dorsal and one anal fin. The 
Ling ( Lota) differs from the latter in having a beard, 
while the Torsk ( Brosmius) has only a single long dorsal fin. 
The Flat-Fish ( Pleurouectidce ) are peculiar amongst 
all the vertebrated animals, in having both eyes placed on 
one side of the head, which side is always uppermost when 
the fish swims, and strongly coloured, whilst the other is 
white. The body is compressed, fringed above by a long 
dorsal, and below by an anal fin. They live constantly in 
shallow water, near the shore. They are liable to varieties; 
sometimes both the upper and under side are dark-coloured, 
d 2 
