80 "SKATES. 



seen the heart of the Common Skate wounded and cut from 

 the body, and aftei wards it has continued to beat for ahnost 

 a whole day; and even when pulsating action has ceased it 

 has again been .nade to resume its motion on the infliction 

 of an additional stimulus. Nor is this power of retaining 

 vitality confined to the heart, or to a single species of this 

 fiimily, although it may be more persistent in some than in 

 others. I have given instances in the Blue Shark of the 

 little present influence had on that fish by what at last 

 cannot have failed to prove fatal injuries, and I shall adduce 

 others not less surprising when we treat of the history of the 

 Common Skate; but in every case it has its source in the 

 same cause the possession of a large degree of independent 

 vital power in each organ of the body. 



Monro, in the work already quoted, has shewn that there 

 exists in this class of fishes, or at least in the Common Skate, 

 as well as in the Monkfish, a well-developed apparatus for 

 the faculty of hearing, the presence of which appears to imply 

 a ijower of intelligence for which we could scarcely have 

 given them credit; but the most remarkable of the organs of 

 sense are the eyes, which are more elaborately organized than 

 even in the Sharks, and which therefore are well calculated 

 to render these fi^^hes effectual service in their situation close to 

 the ground. They are placed on the top of the head, not very 

 close to each other, with the vision neither directed upwards 

 nor forwards, but sidewise, and they are protected as well, by 

 generallv a row of spines behind them, as by a firm structure 

 of cartilage on the upper part of the globe itself. This globe 

 is supported on the base of the ocular cavity by a pillar not 

 unlike that already mentioned as existing in Sharks; but, in 

 addition to this, the cornea or clear portion of the organ is 

 furnished with a veil, which hangs from the upper border of 

 the iris, and in a large degree covers the pupil, and is capable 

 of doing so entirely. The ordinary opinion among naturalists 

 concerning this curtain is, that it is of use in enlarging or 

 diminishing the opening of the pupil, according to the degree 

 of light that is poured on the nerve of sight, as the fish may 

 be exposed to its influence by rising or falling in the water. 

 But I feel disposed to believe that this is not the only nor even 

 the principal use of this beautiful piece of workmanship, of which 



