TWO CILIATA OF GREAT SALT LAKE. 



279 



second tongue-like undulating membrane extends out of the 

 mouth and forward along the floor of the peristomial region. 

 The cytopharynx is a short swollen tube that extends from the 

 mouth backward with a left dorsal deflection. There may be as 

 many as thirty food vacuoles in the body at one time. The 

 remains of the food vacuoles pass out through the posterior 

 dorsal anus. The contractile vacuole is situated in the fore 

 part of the body. The nucleus is situated midway along the 

 body in the left dorsal quarter. This form derives its color 



FIG. 3. Prorodon utahensis. cs, cytostome; c, cilium; fv, food vacuole; cv, con- 

 tractile vacuole. 



from chlorophyll, which is probably in the form of symbiotic 

 alga. 



This form takes food in the form of bacteria, small plants and 

 animals which abound in the water. It is a very active form, 

 having a creeping or swimming forward movement of 100 mic- 

 rons per 7 seconds and a darting backward movement of double 

 this speed. This backward movement generally follows irri- 

 tation at the anterior end. This form when kept in a saturated 

 solution was found to be sensitive to a flash of light from the 

 mirror of the microscope. 



