These worms have the strange power of regenerating lost parts; mutilated portions are soon repaired. The anterior end, when severed from the rest of the body, grows again into a complete individual, while the posterior end continues to perform part of its functions and retains its vitality for a considerable time before dying. One species, /Lineus sanguineus/, is capable, after being broken in pieces, of regenerating each section into a perfect worm. [pg169] The nemerteans are carnivorous, voracious, and often cannibalistic. They will live for some time in confinement, losing, however, their bright color, and the smaller worms will gradually disappear, as they are devoured by the larger ones. The mode of locomotion varies with the order. Some species attach their long proboscis to a distant object, then drag the body to it; some glide rapidly along by means of the muscles of the body and the cilia which cover it; others swim. The swimming forms have thin edges which have a wave-like motion, and this, together with a lateral movement of the tail, propels them through the water. In some species the worm develops directly from the egg; others pass through a larval stage before reaching maturity. GENUS ^Tetrastemma^ ^T. arenicola.^ Dark flesh-color or purplish; slender, cylindrical, four to five inches long when extended; head changeable in form and partly distinct from body because of slight constriction at the neck. It lives in sand at low-water mark. GENUS ^Nemertes^ ^N. socialis.^ Individuals very slender, five to six inches long when extended; color brown or black, a little lighter underneath; three or four eyes in lines on each side the head. It is abundant under stones on rocky shores, many coiled together, forming large masses. ^N. viridis.^ Color olive-green or brown, crossed by faint pale lines; body changeable in form; when extended, six to eight inches long, one eighth of an inch or less in breadth; row of dark eyes on each side of flat head. Common under stones between tide-marks on northern rocky shores. GENUS ^Meckelia^ ^M. ingens.^ One of the largest nemertean worms; found on sandy and muddy shores near low-water mark. The young, from several inches to a foot long, are common. When full-grown some attain the length of twelve or thirteen feet, and are an inch in breadth and quite flat when extended, but can contract to two or three feet in length, and are then nearly cylindrical. This worm, although so soft, penetrates the sand with great rapidity. Its head changes shape constantly and assists the proboscis when burrowing. It is also able to swim. Its color is yellowish or flesh-color, with whitish edges and a central band. ^M. rosea.^ The largest specimens are six to eight inches long and one quarter of an inch broad; lives in burrows on sandy beaches; color red or pink; often covered with sand, which adheres to the mucus which the worm secretes. [pg170]