All winter long the ebony forms of crows vibrate back and forth across the cold sky. If we watch them when very high up, we sometimes see them sail a short distance, and without fail, a second later, the clear "_Caw! caw!_" comes down to us, the sound-waves unable to keep pace with those of light, as the thunder of the storm lags behind the flash. These sturdy birds seem able to stand any severity of the weather, but, like Achilles, they have one vulnerable point, the eyes,--which, during the long winter nights, must be kept deep buried among the warm feathers.
We have all looked down through the clear water of brook or pond and watched the gracefully poised trout or pickerel; but have we ever tried to imagine what the life of one of these aquatic beings is really like? "Water Babies" perhaps gives us the best idea of existence below the water, but if we spend one day each month for a year in trying to imagine ourselves in the place of the fish, we will see that a fish-eye view of life holds much of interest.
What a delightful sensation must it be to all but escape the eternal downpull of gravity, to float and turn and rise and fall at will, and all by the least twitch of tail or limb,--for fish have limbs, four of them, as truly as has a dog or horse, only instead of fingers or toes there are many delicate rays extending through the fin. These four limb-fins are useful chiefly as balancers, while the tail-fin is what sends the fish darting through the water, or turns it to right or left, with incredible swiftness.
If we were able to examine some inhabitant of the planet Mars our first interest would be to know with what senses they were endowed, and these finny creatures living in their denser medium, which after a few seconds would mean death to us, excite the same interest. They see, of course, having eyes, but do they feel, hear, and smell!
Probably the sense of taste is least developed. When a trout leaps at and catches a fly he does not stop to taste, otherwise the pheasant feather concealing the cruel hook would be of little use. When an animal catches its food in the water and swallows it whole, taste plays but a small part. Thus the tongue of a pelican is a tiny flap all but lost to view in its great bill.