On muddy shores the eel-grass (/Zostera marina/) grows abundantly, giving an appearance of submerged meadows. It is one of the very few flowering plants which live in salt water. In summer its little green blossoms may be seen in grooves on the leaf-like blades. Many animals live on and among eel-grass. Found upon it is the delicate gasteropod mollusk /Lacuna vincta/, and its eggs in little rings; the iridescent /Margarita helicina/, and /Nassa/, with its bright-yellow eggs in small gelatinous masses; also little worms (/Spirorbis/) in tiny flat spiral shells, compound ascidians in jelly-like masses, clusters of shelly or horny polyzoans, isopods, planarian worms, and so on. Scallops (/Pecten/) will be found at the base of the plants, and the common prawns are very numerous, swimming freely about. Mud flats and shores are the homes of many mollusks, especially of /Nassa obsoleta/,—which is the most abundant shell of any considerable size from Cape Cod to the Gulf of Mexico,—and of vast numbers of the tiny /Littorinella minuta/, which serve as food for fishes and aquatic birds. Clams and worms of all varieties are also abundant. There are many varieties of mud-crabs, of which the most common are the "fiddlers," which honeycomb the banks and the surface of salt-marshes with their burrows. The common edible crab /Callinectes hastatus/ is plentiful in bays and estuaries. The sluggish spider-crabs hide beneath the surface of the mud and in decaying weeds and eel-grass. Hermit-crabs are plentiful here as well as elsewhere. /Panopeus/ is a sluggish crab found in shallow water and in all sorts of hiding-places along the shore. It [pg013] may often be found in dead shells, and, in the South, in holes in the banks. This genus is represented by a number of species, some of which are quite pretty. WHARVES AND BRIDGES On the piles of wharves and bridges may often be found beautiful tubularian hydroids in large tufts just below low-water mark, branched hydroids looking like little shrubs, polyzoans, sea-anemones, mollusks, and ascidians. The species peculiar to these localities are the boring mollusk /Teredo navalis/, or ship-worm, the boring isopod /Limnoria lignorum/, and the boring amphipod /Chelura terebrans/, all of which penetrate the wood and are most destructive. The animals and plants of tropical beaches and coral reefs are so various and abundant, so curious and beautiful, as to make a description or even an enumeration of them in a brief space difficult. The collector is bewildered and excited when he first views the profusion of the wonderful forms there found.