104 THE OCEAN WORLD. 
Among the forms closely related to this group may be noted the 
Kondylostoma patens (Fig. 38), remarkable for its size and voracity. 
It sometimes attains to the size of the twelfth of an inch, and abounds 
on every shore from the Mediterranean to the Baltic, living among 
alge. Another Bursarian, a species called Lumbrict, lives between 
Fig. 38.—Kondylostoma patens (Duj.), magnified 350 times. Fig. 39.—Stentor Muelleri (Ehr), 
the intestines and the external muscular coat of the earth-worm, 
Lumbricus terrestris. ; 
To the group of Vorticellina belongs the genus Stentor, some 
species of which are quite perceptible to the naked eye. 
The Stentors are inhabitants of fresh, tranquil water, not subject 
to agitation, and- covered with water plants. They are nearly all 
coloured green, blackish, or blue; their bodies are covered with 
cilia, They are eminently contractile, and very variable in form. 
Their body is without a stalk, but they can attach themselves 
temporarily by means of the posterior extremity of their body ; they 
