A weird and stealthy process is this invasion of the ocean, which leads to the alteration and amendment of the surface of the globe. Here, may be watched the very growth of land--land creeping silently, irresistibly upon the sea, yet with a movement which may be calculated and registered with exactitude. Having fulfilled its purpose, the mangrove suffers the fate of the primitive and aboriginal. Tyrannous trees of over-topping growth, which at first hesitatingly accepted its hospitality, crowd and shove, compelling the hardy and courageous plant to further efforts to win dominion from the ocean. So the pioneer advances, ever reclaiming extended areas as the usurping jungle presses on its rear. Nor must it be imagined that mangrove swamps are unproductive. Fish traverse the intricacies of the arching roots, edible crabs burrow holes in the mud, and in them await your coming, and more often than not baffle your ingenuity to extricate them. Among other stalked-eyed crustaceans is that with one red, shielding claw, absurdly large, and which scuttles among the roots, making a defiant clicking noise--the fiddle or soldier crab (GELASIMUS VOCANS). Oysters seal themselves to the roots, and various sorts of shell-fish gather together--two or three varieties appear to browse upon the leaves and bark of the mangroves; some excavate galleries in the living trunks. The insidious cobra does not wear any calcareous covering beyond the frail tiny bivalves which guard the head--a scandalously small proportion of its naked length--but lines its tunnels with the materials whence shell is made, smooth and white as porcelain. How this delicate creature with less of substance than an oyster--a mere worm of semi-transparent, stiff slime--bores in hard wood along and across the grain, housing itself as it proceeds, and never by any chance breaking in upon its neighbours, though the whole of the trunk of the tree be honeycombed, savours of another wonder. Authorities consider the bivalve shell too delicate and frail to be employed in the capacity of a drill, and one investigator has come to the conclusion that the rough fleshy parts of the animal, probably the foot or mantle, acting as a rasp, forms the true boring instrument. Thus, the skill of a worm in excavating tunnels in wood puzzles scientists; and the cobra is certainly among the least conspicuous of the denizens of a mangrove swamp, and perhaps far from the most wonderful.