552 THE OCEAN WORLD. 
fishes by the formidable weapon which it carries in its head. This. 
weapon is a prolongation of the muzzle, which, in place of being. 
rounded off or reduced to a point, forms a long, strong, straight 
sword-like termination, flat on both sides, but on the two edges 
it is furnished with numerous strong teeth of considerable length, 
which are prolongations of the hard, bony substance which forms. 
the muzzle—forming, in short, a sword-blade deeply toothed on 
each edge. 
Thus armed, the saw-fish, as it is sometimes called, the length of 
which is from twelve to fifteen feet, fearlessly attacks the most 
formidable inhabitants of the sea. With its threatening weapon, 
sometimes two yards in length, it dares to measure its strength even 
with the whale. All fishermen who visit the northern seas assert 
that the meeting of these ocean potentates is always followed by a 
combat of the most singular kind, in which the activity of the sword- 
fish is a match for the formidable strength of the whale. Occasionally 
it dashes itself with such force against the side of a ship, that its 
sword is broken in the timber. In the British Museum the blade of 
a sword-fish may be seen which was thus implanted in the timber of 
a ship. 
IV.—GANOIDEA. 
In this order the gills are free and pectinated, as in the ordinary 
fishes. In the sturgeon the gill-openings present a single, very wide 
orifice, with an operculum. They are fishes of great size, living in 
the sea, but ascending the larger rivers in the spawning season. Our 
space only permits us to notice the Sturgeon, which belongs to the 
cartilaginous sub-order of the Ganoids ; a second sub-order contains. 
Ganoid fish with bony skeletons, such as the Bony Pike of the United 
States (Lepidostens osseus). 
The Sturgeons (Acipenser) are among the largest fishes known. 
Their muscles, however, are less firmly knit, their flesh more delicate, 
and their muscular strength is less than one would think from their 
great size ; their mouths, instead of being armed with so many rows. 
of teeth, are funnel-shaped and protrusible, and adapted for sucking, 
up particles of food ; they are not voracious, and their habits are not 
at all ferocious. 
The Sturgeons are sea-fishes, periodically ascending and sO- 
journing for a time in the larger rivers of Europe. They abound in 
the Black Sea and Sea of Azof, but they are chiefly known as. 
frequenting the Volga and the Danube. The enormous consumption 
of caviare in Russia leads to a deadly pursuit of the common sturgeon. 
