THE OUTCASTS OF ANIMAL LIFE. 137 
blood of their hosts, find both food and shelter. 
And others, finding no place for them at all in the 
outer world, burrow into the very body of their 
victim, and feed upon the soft parts within. 
Among these last, the greater number are a low 
race of soft-bodied worms, whose ancestors, when the 
other forms of life — the star -fish, mollusca, ringed 
animals, and insects — found new ways of gaining 
their livelihood, remained behind, groping in the 
mud and sand of rivers and seas, and flapping about 
by the broad margins of their flat bodies. Some of 
the descendants of these soft-bodied worms still 
manage to live a free and independent life. One 
set called the wheel-worms,* because of the curious 
whirling appearance of their lashes as they swim 
about, may be seen under the microscope in almost 
any stagnant water. Another group, with tiny red 
eye -specks, and a trumpet -shaped mouth in the 
middle of their bodies,! live on the sea-shore or in 
ditches, and may be found as little jelly-lumps upon 
water-cresses before they have been washed. An- 
other set,J known as the " ribbon-worms," with elastic 
bodies which stretch sometimes to an enormous 
length, are armed with a tiny dagger in the head, 
with which they pierce the soft bodies of animals 
and suck out their juices. One of these called the 
long-worm^ which looks like a dark strip of india- 
rubber as it lies coiled up under stones on the shore, 
has been known to be as much as twenty feet long, 
though only as broad as the blade of a pen-knife. 
These are the more fortunate of the soft-worms 
which have found a place in the outside world ; but 
* Rotifera. t Planaria. + Nemerteans. § Nemertes borlasia. 
