WORMS 169 



The nemerteans are carnivorous, voracious, and often canniba- 

 listic. They will live for some time in confinement, losing, how- 

 ever, their bright color, and the smaller worms will gradually dis- 

 appear, 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. 



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 



IT. 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 formj 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 Meclselia 



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 yel- 

 lowish 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. 



