The Cartilaginous Fishes are divided into three orders.
1. Sturiones (Sturgeons).
FIG. 44.—THE STURGEON (Accipenser sturio).
Sturgeons (fig. 44) are inhabitants of the northern seas, but are occasionally found in our rivers. They have rows of bony plates imbedded in the skin; they sometimes attain the length of twenty feet, but are usually from six to eight feet long. Isinglass is made of the swimming bladder of the Sturgeon, and the roe (dried and salted) forms the "Caviare."
2. Plagiostomi (Wide-mouthed).
FIG. 45.—THE SHARK (Carcharias vulgaris).
The Plagiostomi comprise the Sharks (fig. 45) and Dog-fishes, a most voracious tribe; the White Shark often attains the length of twenty feet. They are terribly famous for their dreadful powers of destruction, swallowing all that comes before them; they are able to bite in two, with one snap of their formidable jaws, the body of any one unfortunate enough to fall in their way; their mouths are armed with several rows of short spear-shaped teeth; the mouth is placed a considerable distance under the head, so that when biting they turn on one side or quite over; they have no gills, but the water passes through five oblong openings on each side. Sailors hold this terrible inhabitant of the deep in great detestation, as well they may, for there are few who have spent many years at sea but can tell of a friend or messmate who has been mutilated or devoured by the Sharks. When sailors catch one, it is hauled on deck and killed with great gusto; the stomach is opened and its contents examined, and it generally contains some terrible mementoes in the form of buttons, buckles, &c., the only relics of its victims.