90 
room xi. and their flesh is said to be unwholesome. They 
are chiefly found in the Torrid Zone, living 
upon sea-weeds. Others, as the Unicorn File 
Fish ( Monacanthus ), have the skin covered with 
small hairy scales, and the first dorsal consisting 
of only one spine. The Two-spined File Fish 
( Triacanthus ) has a silvery skin covered with 
small scales, and a ventral fin, consisting of a 
single spine, on each side. 
The Trunk Fish ( Ostraciori ) has the same 
elongated form as the Two-spined File Fish, 
and the body covered with an inflexible case 
formed of regular bony compartments. It has 
a very large liver, yielding a considerable quan¬ 
tity of oil, but very little flesh. The body is 
often armed with spines, and according to its 
form, and the position of the latter, the species 
have been distinguished. 
The cartilaginous fishes are entirely without 
any maxillary or intermaxillary bones, their 
teeth being inserted on the palate and vomer. 
Their skeleton is essentially cartilaginous, in 
which the calcareous matter is deposited in the 
form of grains, and their skull is formed of a 
single piece, without any suture. 
The Sturgeons have their gill-flap open like 
the other fishes. Their body is protected by 
bony plates implanted in the skin, and arranged 
in longitudinal rows; their mouth is small, de¬ 
stitute of teeth, and placed at the base of an 
elongated 
