has been seen to rip up the belly of an opponent, so that he sank to the bottom and died of his wound.

The annexed figure of the Saw-fish (Fig. 136), represents its peculiar weapon; that of the Sword-fish (Fig. 137) is still more formidable. The upper jaw forms the sword, which is frequently three or four feet long. The fish occasionally attains a length

of more than twelve feet, and
a weight of more than four
hundred pounds. It is a com-
monly received opinion, that
the Sword-fish has a great
hostility to the whale, and that
whenever it drives its sword-
like beak into the hull of a ship
at sea, the vessel has been mis-
taken for that animal.

The force with which this
is done must be very consider-
able, for not only is the copper
sheathing of the vessel occa-
sionally pierced, but even seve-
ral inches of the solid timber.

FISH.

vib

Fig. 136.-SAW-FISH. Instances are even recorded of Fig. 137.-Swordvessels having suddenly sprung a leak, and being with difficulty got into port, from injury thus occasioned by the Sword-fish.

A still more remarkable mode of defence is, that of giving a severe electric shock. The Torpedo, or Electric Ray of our own shores (Fig. 138), is one exam

ple of this; and another is furnished by the Electric Eel of the South American rivers, whose shock is sufficiently powerful to stun and even destroy horses.

Fig. 138.-TOR

PEDO.

divided into

The skeleton of some fishes is composed of cartilage or gristle, that of others is of bone. Fishes are, therefore, arranged in two great divisions, according to the nature of the skeleton. Those which have the skeleton of bone form much the more numerous group: this is two other groups, in one of which the fins upon the back are composed wholly or in part of stiff rays united by a membrane; and in the other the fins have soft flexible rays, dividing into numerous branches. The groups thus formed are again subdivided, according to the presence or absence of certain fins-the difference in their relative positions the variety in the structure of the gills and gillcovers, and other details of secondary importance. In this way, according to Cuvier's classification, all fishes are arranged in nine Orders, three of them being devoted to the "cartilaginous," or those which have the skeleton of cartilage or gristle, and six to the "osseous," or those in which the skeleton is formed of bone.

CARTILAGINOUS FISHES.

ORDER I.-LAMPREYS.

THE first order of these fishes has its peculiarities well exhibited in the River Lamprey (Fig. 139). A row of circular

openings along each side of the neck, leads to gills of a corresponding form; and the circular mouth by means of which the fish can adhere to stones, has procured for the family a scientific name which signifies "stone-suckers."

ORDER II.-SHARKS AND RAYS.

THESE fishes, though differing much in external form, belong to the same group-one which is distinguished by the structure of the gills, the long-shaped gill-apertures on the neck, and the peculiar form of the mouth.

16

The figure (Fig. 140) represents the small-spotted Dogfish, one of the family of the Sharks, and an object of great

dislike to fishermen, because of the injury which they believe it causes to their fishing.

The eggs of both Sharks and Rays are few in number, and are not deposited on the sand or gravel, but each egg is enclosed, for greater safety, in a horny case, attached by long tendrils to the larger sea-weeds; and among the Sharks of the largest size, some bring forth their young alive. The empty egg-cases are frequently found on the sea-shore, and

Fig. 141.-EGG-BAG, WITH YOUNG SHARK,

are well known by the name of " sea-purses,'

"mermaids'

purses," and other local terms. The longer and narrowershaped belong to the Sharks and Dog-fishes; the broader and shorter ones to the Skates or Rays. The figure (Fig. 141) represents the case laid open, and the young Dog-fish, attached to the "yoke," or membranous bag of nutriment. Water is admitted by means of a slit at each end of the purse.

The Sharks are very tenacious of life, and some of them attain a great size. The Basking Shark, a species found off these coasts, has been known to measure thirty-six feet in length, and is one of the largest of the true fishes.

ORDER III.-STURGEONS.

IN the third order of Cartilaginous fishes, there is an approach, in some points to those belonging to the other great group. The gills are comb-shaped, and there is

Fig. 142.-STURGEON.

one large gill

aperture. This

group is repre

sented by the Sturgeon (Fig.

142), a fish which attains so large a size, that one taken in the Esk weighed 464 lbs. The form of the tail in the Dogfish (Fig. 140) and the Sturgeon (Fig. 142) is very unlike that of the Pollan (Fig. 149) or the Pilot-fish (Fig. 152), and forms one of the most obvious external characters by which the Cartilaginous fishes may be distinguished from the Osseous.