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THE POPULAR SCIENCE MONTHLY. 





fish aided by the thresher-shark. The fierce gladiator was said to 

 attack from below, goading his mighty adversary to the surface with 

 his terrible weapon, while the thresher, at the top of the water, be- 

 labored him with bis long, 

 lithe tail. Skeptical modern 

 science is not satisfied with 

 this interpretation of any 

 combat at sea seen at a dis- 

 tance. It recognizes the 

 improbability of aggressive 

 partnership between two 

 creatures so different as the 

 sword-fish and a shark, and 

 explains the turbulent en- 

 counters occasionally seen 

 at sea by ascribing them to 

 the attacks of the killer- 

 whale upon larger species 

 of the same order. 



Such a large animal as 

 the sword-fish can have but 

 few formidable antagonists. 

 The tunny, or horse-mack- 

 erel, other sword-fishes, and 

 sharks, are its only peers in 

 size, and of these the sharks 

 are probably its worst foes. 

 Mr. John A. Thomson, of 

 New Bedford, states that 

 the bill-fish is an inveterate 

 enemy. Bill -fish appear 

 about the last of the season, 

 and the sword-fish are sure 

 to leave soon after. Many 

 species of parasites are 

 found upon the sword-fish ; 

 some hang on the gills, 

 others fasten themselves to 

 different parts of the ali- 

 mentary canal, and others still bore into the flesh. They may be divided 

 into two groups, worm-like parasites and crustacean pai-asites, the latter 

 resembling small crabs and lobsters. Several species, as might be ex- 

 pected from the size of the fish, are among the giants of their races. 

 There is also a species of remora or sucker which is often found attached 

 to the gill-cover of the sword-fish, and to no other fish. It is, however, 

 to be regarded as a messmate rather than as a true parasite. 







Fig. 2.— Swoed op Young Stvord-Fish. 



