354 NATUKAL HISTORY OF AQUATIC ANIMALS. 



"A Boston ship hauled up on the ways for repair, a few years 1 since, presented the shank of a 

 Sword-fish's dagger, which had been driven considerably far into the solid oak plank. A more 

 curious aft'air was brought to light in 1725 in overhauling His Majesty's ship 'Leopard,' from the 

 coast of Africa. The sword of this marine spearsmau had pierced the sheathing one inch, next it 

 went through a throe-inch plank, and beyond that three inches and a half into the firm timber. 

 It was the opinion of the mechanics that it would have required nine strokes of a hammer weigh- 

 ing twenty-five pounds to drive an iron bolt of the same dimensions to the same depth in the hull. 

 Yet the fish drove it at a single thrust. 



"On the return of the whale-ship 'Fortune' to Plymouth, Massachusetts, iu 1827, the stump 

 of a sword blade of this fish was noticed projecting like a cog outside, which, on being traced, had 

 been driven through the copper sheathing, an inch board undersheathing, a three-inch plank of 

 hard wood, the solid white-oak timber twelve inches thick, then through another two and a half 

 inch hard-oak ceiling, and lastly penetrated the head of an oil-cask, where it stuck, not a drop of 

 the oil having escaped." 



Such instances could be found by the score, if one had the time and patience to search. The 

 thing happens many times a year, and nearly as often affords a text for some paragrapher or local 

 editor. , 



ENEMIES. Such a large animal as the Sword-fish can have but few antagonists whose attacks 

 would be disastrous. The tunny or horse-mackerel, Orcynus thynnus, other Sword-fishes, and 

 sharks are its only peers in size, and of these the sharks are probably its worst foes. 



Capt. N. E. Atwood exhibited to the Boston Society of Natural History, December 7, 1864, 

 the lower jaw of a large shark, taken at Provincetown, Massachusetts, in whose stomach nearly 

 the whole of a large Sword-fish was found. Some ten or twelve wounds were noticed in the skin 

 of the shark, giving an idea of the conflict. The shark was doubtless Galeocerdo tigrinus. 



Couch was told by a sailor that he had watched with interest the anxious motions of one as it 

 was followed closely and rapidly in all its turnings by a blue shark. Twice did it leap above the 

 surface to escape the near approach of its pursuer, but with what success at last the observer had 

 no opportunity of knowing. 



Mr. John H. Thomson states that the Bill-fish (probably Tetrapturus albidus) is their especial 

 enemy. Bill fish, six to twelve feet long, appear about the last of the season, and their appear- 

 ance is a signal that the Sword-fish are about leaving. 



INVERTEBRATE PARASITES OF THE SWORD-FISH. Aristotle thus explains the leaping move- 

 ments of the fish : "The tunny and the Xiphias suffer from the oestrus at the rising of the dog star, 

 for both these fish at this season have beneath their fins a little worm which is called oastrus, 

 which resembles a scorpion, and is about the size of a spider; they sutfer so much from this 

 torment that the Xiphias leaps out of the sea as high as the dolphin, and in this manner fre- 

 quently falls ui)on our ships." 



This description of the parasite is somewhat vague; yet it is evident that allusion is made to 

 one of the Lerneans or gill-lice, little crustaceans remotely resembling crabs and lobsters, which 

 attach themselves to the gills and skin of many kinds of fishes, sucking the blood from their veins, 

 and often causing death; dreadful to their victims as was their namesake, the fabled Leruean 

 Hydra, to the Argives of old, and not to be destroyed by any piscine Hercules and lolaus. 



In one of the early volumes of the " Philosophical Transactions" is an account by S. Paulo 

 Boccoue of "an extraordinary Sanguisuga, or Leech, found sometimes sticking fast in the Fish 

 called Xiphia or Sword-fish," It is described as "about four Inches long, the Belly of it white, 

 cartilaginous and transparent, without Eyes or Head, but instead of a Head it had a hollow Snout, 



