All the others there become more than the term “fish” when you see them suspended behind glass, floating in their own world of water, strangers in the perfection of their own remoteness. Their dull jaws open and close as they breathe. Their filmy, diaphanous fins wave lightly and loosely. Their flicking eyes pass you by, with a kind of self-enclosed abstractness, a stiffness, as if they had not seen you at all, and no doubt the blurred human form means very little to them. The glass separates the world of water from the world of air. Their bodies curve deliberately and slowly, and then suddenly switch into an unsuspected quickness, while we tourists shove and crowd and gawk from our unbridgeable distance. At other windows the rays and skates, with fins fused to bodies like wafers, wave through the water. Bottom fish suddenly disappear in puffs of sand. The lean, long sand shark, primitive, tough, swims with infinite smoothness back and forth, an expression of coldness, an incarnate simplicity. They are all unknown, not of our race, and giving the unknown the old credit of fear, they _are_ horrible, monsters in their realm, with intercommunications, receptions, that we are unable to touch. An aquarium is a luxury. Most of the fish we see are dead, a boatload of wet, cold, slippery white and gray flounder, cod, or haddock just come into port, or dying, like a striped bass caught by a fisherman casting off the beach--flipping on the sands with all its cool brightness still alive, a slippery, lucent sea green. The color loss is quick as a fish dies, leaving the rippling shades of its great medium behind. The world of ocean color comes inland in the spring with the alewives that migrate from salt water up inlets, streams, and estuaries on both sides of Cape Cod. They are silver, like the sea they come from, with backs of gray green, and in a shallow stream they seem to reflect the colors of the season, having in fact the ability to change the pigment in their skin so as to blend with their surroundings. They mouth the water and stare forward with their big eyes, running upstream with the unswerving directness of their need to reproduce--which gives us at least one reassuring alliance with them!--and being of a fairly large size compared with most fresh-water fish, they have a look of marine capacities, a fast-schooling fish made for water masses, great sweeping currents, and tides.