80 
"IKATES. 
seen the heart of the Common Skate wounded and cut from 
the body, and aftei wards it has continued to beat for almost 
a whole day; and even when pulsating action has ceased it 
has again been made 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 
family, 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 power 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 fishes 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 
generally 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 dalling 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 
