74 CHAPTERS ON THE NATURAL HISTORY 



tail, a questionable statement, though it is known that these 

 sharks feed upon fish. 



Most of the sharks are viviparous, but the dogfishes piroduee 

 eggs closely resembling those brought forth by the rays. When 

 a boy, 1 frequently found them at low water on Long Island 

 Wound, tangled up in the salt water grass. Some sharks are 

 bottom-loving species, while a few species may almost be reck- 

 oned among the so-called deep-sea fishes. Two small species of 

 dogfishes have been taken at depths varing between 400 and 500 

 fathoms, or nearly 3,000 feet below the surface. Gunther says 

 these sharks were from three to four feet long, and " on being 

 rapidly withdrawn from the great pressure under which they 

 lived, they were killed, like other deep-sea fishes, under similar 

 circumstances." 



Some naturalists claim that the oldest existing type of verte- 

 brate is a shark, it comes from Japan, and only two specimens 

 of the species have thus far fallen into the hands of science. One 

 of these is in the Museum of Harvard College, and the other is 

 in the British Museum. Our distinguished countryman, Mr. 

 Samuel Garman, of Harvard, was the first man to describe this 

 remarkable shark, and he gave it the scientific name of Glila- 

 mydoselachus anguineus. A few years ago 1 received from him a 

 copy of his memoir on the subject, and I have copied his figure to 

 show the appearance of the fish here. (Fig. 13.) 



As I have just said above, some of our sharks may almost be 

 classed among those oceanic forms of fishes, that living so far be- 

 neath the depths of the seas are now universally termed by nat- 

 uralists the deep-sea fishes, and by the aid of our modern 

 oceanic dredging machines we are coming to know something 

 of these remarkable forms. Many invertebrates are also thus 

 taken, but after all it is the extraordinary types of fishes that 

 from time to time have come to light which have possessed the 

 keenest interest for the ichthyologist and marine naturalist. 

 Many of these have long been known, but a few years ago 

 the splendid researches of the British Challenger expedition 

 greatly increased our knowledge of them. Ingenious nets and 

 trawls have brought up, from depths varing from 200 to 2,400 

 fathoms, many genera and species of these curious fish, repre- 

 senting, as they do, some dozen or more families. As a fathom 

 is six feet, this means from 1,200 to 14,400 feet, a fact in itself 

 sufficient to excite our wonder. Most all the great oceans and 



