OTHER PROTOZOA 
149 
125. Economic Importance. — Paramecia consume con¬ 
siderable quantities of bacteria, but whether more harmful 
than helpful ones cannot be told. Therefore their eco¬ 
nomic value is uncertain. 
126. Other Protozoa. — If one examines stagnant water, 
a large number of other kinds of Protozoa will be found. 
The more common forms are much like the paramecium 
and have many cilia on the body. Several of these large, 
ciliated Protozoa feed on the smaller Protozoa. Some of 
the common forms are shown in Figures 139-141. 
Figure 140 . — One of the 
Foraminifera. 
Figure 141 . — Some Flagellate Pro¬ 
tozoa. 
All these various Protozoa can be grouped into classes, 
each with certain distinct characteristics. For instance, all 
Protozoa that have pseudopodia are called Rhizopoda. In 
this group, the cells may be naked or may possess a hard 
mineral covering \ a second group of Protozoa are provided 
with one or more long, wavering threads called flagella 
(fla-jel'la: Latin, flagellum , whip), and have the name 
Flagellata; the flagella are longer than cilia and exhibit 
more complicated movement. A third class, known as 
Infusoria (in-fu-so'ri-a), includes most of the common Pro¬ 
tozoa found in protozoan cultures. Most of this class are 
provided with cilia. 
