Mr. Pennant says that this snake (rattle-snake) will frequently lie at the bottom of a tree on which a squirrel is seated. He fixes his eyes on the animal, and from that moment it cannot escape; it begins a doleful outcry, which is so well known that a passer-by, on hearing it, immediately knows that a snake is present. The squirrel runs up the tree a little way, comes down again, then goes up, and afterwards comes still lower. The snake continues at the bottom of the tree with its eyes fixed on the squirrel, and his attention is so entirely taken up, that a person accidentally approaching may make a considerable noise without so much as the snake turning about. The squirrel comes lower, and at last leaps down to the snake, whose mouth is already distended for its reception. Le Vaillant confirms this fascinating terror by a scene he witnessed. He saw on the branch of a tree a species of shrike, trembling as if in convulsions, and at the distance of nearly four feet, on another branch, a large snake that was lying with outstretched neck and fiery eyes, gazing steadily at the poor animal. The agony of the bird was so great that it was deprived of the power of moving away; and when one of the party killed the snake, it (_i.e._ the bird) was found dead upon the spot--and that entirely from fear; for, on examination, it appeared not to have received the slightest wound. The same traveller adds that a short time afterwards he observed a small mouse in similar agonising convulsions, about two yards from a snake, whose eyes were intently fixed upon it; and on frightening away the reptile, and taking up the mouse, it expired in his hand.[142] Many other observations, more or less similar, might be quoted; but, on the other hand, Sir Joseph Fayrer tells me that 'fascination is only fright;' and this appears to be the opinion of all persons who have had the opportunity of looking into the subject in a scientific manner. The truth probably is that small animals are occasionally much alarmed by the sight of a snake looking at them, and as a consequence of this more easily fall a prey. In some cases, it is likely enough, strong terror so unnerves the animal as to make it behave in the manner which the witnesses describe; in making half-palsied efforts to escape, it may actually fall or draw nearer to the object of its dread. Perhaps, therefore, Dr. Barton, of Philadelphia, is a little too severe on previous observers when he says that--