EDMONDSON — PROTOZOA OF IOWA. 77 



associated with ParaiiKcciuin caudatuvi, and is widel}- distributed 

 over the state. 



Plant tissue seems to be the chief food of this species, indi- 

 viduals being frequently observed almost entirely filled with 

 algae filaments, diatoms, etc. When this variety of food is not 

 to be obtained, however, the organism may adopt a carnivorous 

 habit, on one occasion a large specimen having been seen to have 

 ingested four rotifers. The anal opening is near the posterior end 

 at right-angles to the mouth. 



Trichocysts are highly developed in this species, various 

 chemical stimuli causing them to be extended far beyond the 

 cilia and often cast entirely from the body. 



Reproduction takes place by transverse division, a new oral 

 aperture appearing even before constriction of the cell com- 

 mences. The nucleus is concealed during life and I have not been 

 able to demonstrate its nature or position, even by the aid of 

 stains. 



Figure 123, Plate XVI, represents a species found in Johnson 

 county among algae, which probably should be classified under 

 this genus. The body is palstic but usually oval and densely 

 packed with globular food-masses. The oral aperture has not 

 definitely been made out although a slit-like opening, lateral and 

 anterior in position, may sometimes momentarily be seen, but 

 immediately closes. Contractile vesicle single. The nucleus, by 

 the aid of reagents, is found to be greatly elongated in a medium 

 plane of the body. I have not made a sufficient study of the 

 organism to accurately determine its identity. 



OPHRYOGLENA Ehrenberg. 



Somewhat oval, flattened ventrally, convex dorsally. Oral 

 opening anterior to the center of the body, provided with a 

 vibratile flap-like membrane. Trichocysts often present. 



Ophryoglena atra I^hr. 



Body rounded anteriorly, posterior extremity pointed. Endo- 

 plasm usually dark colored and opaque with a very dark blue 

 pigment spot in the anterior region. Nucleus round, posteriorly 

 situated. Contractile vesicle central. 



I^ength, 125-150 microns. Fig. 124, PI. XVI, a ventral view 



