298 NATURAL HISTORY. 



In the same cut with our common dog-fish is shown (the lower figure) 

 the smooth-hound, also an American species, but one which has none of 

 the voracity of its fellow. Indeed, it is not fitted for such a rapacious life, 

 for its teeth are of an entirely different character from those of most 

 sharks. Instead of being sharp and of a cutting nature, they rather 

 resemble the pavements of our streets. When we consider the nature of 

 the food, we see at once how well these teeth are adapted to their purpose. 

 These smooth-hounds feed upon crabs and shell-fishes, and these teeth, like 

 the jaws of a stone-crusher, are admirably adapted to breaking the shells 

 of these animals, thus rendering them in a condition suitable for digestion. 



The series of sharks is a rather long one, there being about a hundred 

 and fifty species known ; and our space will admit of mention of but a few 

 of the more interesting forms. All are marine with one exception, — a 

 small form found in Lake* Nicaragua. The largest known form is the whale- 

 shark of the Pacific, which attains a length of fifty, and it is said even of 

 seventy feet, a size which well entitles it to its common name. It is, how- 

 ever, not a dangerous form ; for its teeth are very small, and the animal is 

 said to feed on sea-weed, a statement which, however, needs confirmation. 



Strangest in appearance is the huge hammer-headed shark, which may 

 attain a length of fifteen feet. Its most striking feature is its head, which 

 is queerly drawn out on either side into a shape very like a hammer, the 

 eyes being placed on the ends of the lobes. This species is one of the 

 forms that attack man when occasion offers ; and it is fortunate that it 

 appears but seldom on our northern coasts. In the tropical seas it is very 

 abundant, and the voyager frequently sees them rising from the depths in 

 large numbers, the school presenting the appearance of a cloud. 



This habit, if habit it may be called, of man-eating is common to 

 several species of the larger sharks, so that the term ' man-eater ' . is rather 

 indefinite. Most prominent among these detested forms are the great blue 

 and white sharks, the former reaching a length of twenty-five, the latter 

 of thirty-seven, feet. Still another but less common species is sometimes 

 found forty feet long. The story has often been told of the way in which 

 these sharks will follow a ship, sometimes for days, eating everything that 

 is thrown or falls overboard. The catalogue of things which have been 

 found in their stomachs is enormous, and shows the most omnivorous 

 appetite, or rather, an incontrollable desire to swallow everything that 

 comes in their way. According to Ruysch, the whole body of a man 

 encased in armor was found in a white shark ; while Bluemenbach records 

 the occurrence of a horse in the stomach of another individual of the same 

 species. 



It is no wonder that sharks following a ship day after day arouse the 



