198 THE HAMMER-HEADED SHARK. 



Being brought on deck, however, the struggles of the creature recommence with tenfold 

 violence. Twisting with marvellous agility, snapping right and left with its murderous teeth, 

 and dealing heavy blows with its terrible tail, it makes the deck tremble under its strokes, 

 until some experienced sailor runs in with an axe, and, with a blow across the tail, reduces 

 the creature to malignant impotence. The muscles of the Shark are endowed with astonishing 

 irritability, and long after the body has been cut to pieces and parts of it cooked and eaten, 

 the flesh will quiver if pricked with a knife-point ; the separated heart will beat steadily while 

 lying on the bare boards, and the jaws of the severed head will snap with frightful vehemence 

 if any object be put between the teeth. 



Sailors generally make high festival at the dismemberment of a Shark, and have great 

 delight in opening the creature, for the purpose of finding out the articles which it had swal- 

 lowed. For a Shark, when following a vessel, will eat anything that falls overboard. The 

 contents of a lady's workbox, a cow's hide entire, knives, hats, boots, and all kind of miscel- 

 lanea have been found in the interior of a Shark ; while, on one occasion, were discovered the 

 papers of a slaver, which had been flung overboard when the vessel was overhauled, and, by 

 means of which papers so strangely recovered, the vessel was identified and condemned. 



The color of this species is beautiful slate-blue above, and white below. 



The Blue Sharks are represented in our waters by four species, being very numerous in 

 species in other and tropical seas. 



GREAT BLUE SHARK (Charcharinus glaucus) is a large form of the tropics, occa- 

 sionally found in our American seas. Mr. Couch, the British naturalist, says: "This Shark 

 is so plentiful about the month of June, that nine or ten have been taken in one day." It is 

 a constant and serious trouble to the fishermen. This Shark is one of the kinds that are so 

 frequently taken on ocean-going vessels. 



THE DUSKY SHARK (C. obscurus) is a large one, reaching the length of nine or ten feet. 

 It is very common off the American Atlantic shores. 



THE SMALLER BLUE SHARK (C. milberti) ranges from Cape Cod to Florida, and is also 

 found in the Mediterranean Sea. De Kay says : " This is taken frequently along our shores, 

 and as far north as New Hampshire." 



A SPECIES, C. lamia, was identified by Prof. Putnam from a tooth which is large enough 

 to represent a Shark thirteen feet in length. 



THE remarkable fish depicted in the accompanying illustration affords a striking instance 

 of the wild and wondrous modifications of form assumed by certain creatures, without any 

 ascertained purpose being gained thereby. We know by analogous reasoning that some wise 

 and beautiful purpose is served by this astonishing variation in form ; but as far as is yet 

 known, there is nothing in the habits of this species that accounts for the necessity of this 

 strange shape. 



The shape of the body is not unlike that of the generality of Sharks, but it is upon 

 the head that the attention is at once rivetted. As may be seen from the figure, the head 

 is expanded laterally in a most singular manner, bearing, indeed, no small resemblance to the 

 head of a hammer. The eyes are placed at either end of the projecting extremities, and the 

 mouth is set quite below, its corners just coinciding with a line drawn through the two 

 projecting lobes of the head. It is worthy of notice, that several of the commonest insects 

 those beautiful dragon-flies belonging to the genus Agrion have heads modelled on a very 

 similar principle, and there are some exotic insects where this singular shape is even more 

 < 'x;i gyrated, the eyes being set quite at the end of long lateral footstalks. 



This species attains to a considerable size, seven or eight feet being a common measure- 

 ment, and specimens of eleven or twelve feet having been known. Its flesh is said to be 

 almost uneatable, being hard, coarse, and ill-flavored. 



The HAMMER-HEADED SHARK produces living young, and from the interior of a very fine 

 specimen captured near Tenby, and measuring more than ten feet in length, were taken 

 no less than thirty -nine young, all perfectly formed, and averaging nineteen inches in length. 



