MACKERELS. 121 



vessel through the water must be deducted from 

 the force exerted by the powerful animal. The 

 weapon in this case had penetrated through one 

 inch of sheathing, three inches of planking, and 

 four inches and a half of the solid timber. 



The Sword-fish is the furious enemy of the 

 Whales, including the northern species and the 

 Cachalot ; and many accounts relate the rage and 

 energy with which the armed warrior of the 

 seas attacks his gigantic foe, and seeks to bury 

 his weapon in his mighty sides. And in this 

 animosity a motive has been sought for the sui- 

 cidal assaults already mentioned, the Sword-fish 

 mistaking the hull of the ship, a huge dark body 

 moving through the water, for his enemy, and 

 darting upon it with blind indiscriminating fury. 

 It may be so : but Cuvier mentions a little fact, 

 with which these attacks may not be unconnected. 

 " Notwithstanding its formidable weapon, its 

 great strength, and its ahnost incredible celerity, 

 a small crustaceous animal penetrates the flesh of 

 the Sword-fish, and sometimes so torments it that 

 it dashes itself on the shore with mortal violence." 



3. Centronotina. The form is oblong, or some- 

 times lengthened and slender ; the fore part of 

 the dorsal is superseded by a number of small 

 free spines ; the ventrals are present and perfect ; 

 the body is covered with very small scales. Seventy 

 species are reckoned to belong to this group, 

 which ranges over all seas. The most worthy of 

 notice is the beautiful little Pilot-fish {Nancrates 

 ductor, Linn.), so called because of its constant 

 attendance on Sharks, as well as on ships, a pro- 

 pensity as unaccountable as it is interesting. The 

 fact is indubitable ; we have ourselves witnessed 



