EDMONDSON — PROTOZOA OF IOWA. 69 



extensile. Oral aperture at the base of the neck, often a promi- 

 nent hump or shoulder indicating its position. Pharynx short. 



Nucleus moniliform, extending nearly the length of one side of 

 the body. .Contractile vesicles numerous, arranged in a dorsal 

 row nearly the whole length of the body. 



Trichocysts on the ventral surface of the neck. 



Length of body, 500-800 microns. (Fig. 106, PI. XIV.) 



This species is one of the most elonga'ted free-swimming .species 

 of Protozoa common to this state. The organism is carnivorous 

 in its food habits, smaller animalcules usually being captured by 

 means of the trichocysts and pressed into the oral aperture by the 

 long flexible neck. It has been my observation that the trichocysts 

 are paralyzing in their effect upon the Infusoria, but do not 

 necessarily produce death. Dilcptiis gigas has been seen to 

 paralyze a small holotrichous form with its stinging threads and, 

 in the attempt to ingest it, the victim was pushed entirely out of 

 reach by the long neck of its captor. In a few moments the little 

 organism revived and swam away, leaving Dileptus apparently 

 frantically seeking in all directions for that which had escaped. 



In young individuals the posterior region is usually broadly 

 rounded, the tail-like prolongation being commonly observed in 

 maturer specimens. The nucleus is usually concealed and re- 

 agents may be necessary to render it visible. 



Found in pond water and widely distributed. Reproduction is 

 by transverse fi.ssion. 



LIONOTUS Wrzesniowski. 



Elongated, flexible, with a flattened ciliated ventral and a con- 

 vex dorsal surface. Anterior extremity usually neck-like, pos- 

 terior extremity often pointed, tail-like and curved. Oral aper- 

 ture ventral. Contractile vesicles sometimes numerous. 



L,IONOTUS FASCIOLA Ehr. 



Body elongated, ciliated on the ventral surface only, wider 

 centrally, gradually tapering toward the narrow, flexible neck- 

 like region, the distal extremity of which is often abruptly 

 curved. Posterior extremity rounded, narrow. Oral aperture 

 ventral, an indistinct, slit-like opening some distance from the 

 anterior end. Nuclei, two spherical bodies centrally located. 



