ROOM XI.] NATURAL HISTORY. 49 
In many of these the jaws and palate are full of teeth, 
as in the common pike ( Esox Indus) ; in others, as the 
Gar-Fish (Esox belone), the jaws are slender, and very 
much elongated. In one genus, the Half-Beak ( Hemi - 
ramphus), the lower jaw alone is elongated and the mouth 
oblique, and placed at its base. The Flying-Fish 
(Exocetus) belong to this family ; they inhabit the seas of 
warm and temperate climates, and are peculiar for the 
great length of the pectoral fins, which enables them to 
suspend themselves in the air as long as the fins continue 
moist. On leaving the water, to escape from the pursuit 
of their enemies in that element, they often become the 
prey of birds which are continually on the watch to attack 
them. The Mormyri (Mormyrus) are fresh water fish of 
Africa, which have a small mouth, and the gill-flap hid 
under the skin. 
The Siluroid Fish ( Siluridce ) have a naked skin, in 
which large bony plates are frequently imbedded. They 
have often an adipose dorsal fin, and their intermaxillaries 
form the margin of the upper jaw, their maxillaries being 
reduced to mere vestiges, or elongated into little beards. 
Many of these have the first ray of the pectoral fin very 
strong and bony, and the animal has the power of fixing 
it immoveably, so that it forms a dangerous weapon, and 
the wound inflicted by it is said to be venomous ; but this, 
perhaps, greatly depends on the liability«of persons in 
warm climates to tetanus or locked jaw fn&n penetrating 
wounds. They live chiefly on vegetable food, especially 
seeds. Their flesh is very fat, and much used as food; 
but that of some species, as the Shals ( Synodontes ) of 
Senegal, is reputed to be dangerous. The skin of some 
of the genera, as the Callichtes (Callichtes), is covered 
with four rows of large imbricated scales, which protect 
the body, like scale-armour; and others, as the Loricaria 
(Loficarice) , have the body entirely covered with a hard 
coat, formed of angular scales. 
The Salmons ( Salmonidce ) have, like most of the 
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 
D 
