6. SHARKS AND RAY-FISHES. 



at acute angles. The muscles themselves have a resemblance to 

 those of quadrupeds, and the bundles of fibres which constitute 

 their substance appear to possess the powers of separate action, 

 by which the motions of the fish may be more minutely and 

 effectually regulated. Such muscles as lie behind the ventral 

 fins are accompanied with what may be denominated tendons, 

 which are a portion of animal structure that does not exist in 

 the common class of bony fishes; and by the use of these, which 

 are longer and stouter the nearer they approach the tail, that 

 important organ is enabled to put forth its very powerful action 

 without being itself inconveniently stout. Although the lateral 

 muscles of a fish's body may be said to be innumerable, there is 

 some propriety in considering those of the body of a Shark as 

 forming four of large size, over and above those which are smaller 

 and subordinate; for the tendino-cellular membrane interposed 

 between the skin and muscle passes between those larger masses 

 of muscle, and may be said either to divide or unite them, and 

 at the same time serving to give firmness to their action by the 

 general support it affords them. This description is more es- 

 pecially taken from the Ray-mouthed Dogfish and Toper (Mustelus 

 Icecis and Galeus vulgaris ;) but with some variation it is, doubtless, 

 observable in all Sharks. But it is more distinctly marked in 

 the former species than in the latter, thus directing our views 

 to its importance; and accordingly it has been observed by 

 fishermen that the former fish, when it has taken the hook, is 

 much stronger in the water than the latter. 



It is on account of the particular structure of the muscular 

 layers in Sharks that they are able to direct their motions with 

 greater precision than the generality of fishes, and also that they 

 can continue their efforts without weariness for an almost unlimited 

 duration of time; and accordingly sailors inform us of the vast 

 extent of ocean along which they have been accompanied by 

 some of those fishes, without apparent weariness, when their 

 appetites or expectations have been excited after prey. 



We shall defer the description of the eye of the Hays until 

 we come to speak particularly of that tribe of fishes; but this 

 organ is but little less curious in the Sharks, although its structure 

 is founded on very simple principles as compared with that of 

 other animals. In most kinds of fishes the eyes are round and 

 prominent, without the possibility of being closed, even in sleep 



