264 THE INHABITANTS OF THE SEA. 
In most of the wandering annelides, each segment is pro- 
vided with variously formed appendages, more or less developed, 
serving for respiration and locomotion, or for aggression and 
defence; while in some of the least perfect of the class, not a 
trace of an external organ is to be found over 
the whole body. The great Band-worm 
(Nemertes gigas) is one of the most remark- 
able examples of this low type of annelism. 
, It is from thirty to forty feet long, about 
Aphrodita, or Sea- 5 ‘ é 
Mouse. half an inch broad, flat like a ribbon, of brown 
or violet colour, and smooth and shining like 
lackered leather. Among the loose stones, or in the hollows of 
the rocks, where he principally lives on Anomize, — minute shells 
that attach themselves to submarine bodies, — this giant worm 
forms a thousand seemingly inextricable knots, which he is con- 
tinually unravelling and tying. When after having devoured all 
the food within his reach, or from some. other cause, he desires 
N 
YN 
to shift his quarters, he stretches out a long dark-coloured 
ribbon, surmounted by a head like that of a snake, but without 
its wide mouth or dangerous fangs. The eye of the observer 
sees no contraction of the muscles, no apparent cause or instru- 
ment of locomotion; but the microscope teaches us that the 
Nemertes glides along by help of the minute vibratory 
cilize with which his whole body is covered. He hesitates, he 
tries here and there, until at last, and often at a distance of 
fifteen or twenty feet, he finds a stone to his taste; whereupon 
he slowly unrolis his length to convey himself to his new resting 
place, and while the entangled folds are unravelling themselves 
at one end, they form a new Gordian knot at the other. All 
the organs of this worm are uncommonly simplified ; the mouth 
is a scarce visible circular opening, and the intestinal canal ends 
in a blind sack. 
Nature has not in vain provided the more perfect annelides 
with the bristly feet, which have been denied to the Nemertes 
and the sand-worm. Almost all of them feed on a living prey, 
— Planarias and other minute creatures — which they enclasp 
and transpierce with those formidable weapons. Some, ying in 
wait, dart upon their victims as they heedlessly swim by, seize 
them with their jaws, and stifle them in their deadly embrace ; 
others, of a more lively nature, seek them among the thickets of 
