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. 
Genus Tetrastemma 
L. 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 
ee 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 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. 
