48 
NATURAL HISTORY. [UPPER FLOOR. 
being divided across, so that it appears to have four eyes, 
similar to the Gyrini among the water-insects. The fe¬ 
male is viviparous. 
The family of Pikes ( Esocidce ), also are without any 
adipose dorsal fin. and the upper jaws are edged by the 
intermaxillaries. In most of the genera, the dorsal fin is 
placed opposite the anal. They are generally voracious, 
and prey on smaller fish. 
In many of these the jaws and palate are full of teeth, 
as in the common pike (Esox lucius) ; in others, as the 
Gar-Fish (Esox helone ), 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 w^ater, to escape from the pursuit 
of their enemies in that element, they often become the 
prey of birds which are continually on the w atch 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 from 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 
