158 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Colpidium striatum Stokes. 



Body elongated reniform, at least twice as long as broad. Anterior 

 extremity curved slightly toward the ventral side. Macronucleus 

 spherical, centrally located. Contractile vacuole near posterior extremity. 



Found in abundance in vegetable infusions. • 



Length of type specimen, 110 microns. (Fig. 24, plate XXXVII.) 



Colpidium putrinium Stokes. 



Body ovate, less than twice as long as broad. Anterior end obtusely 

 pointed. Ventral surface flattened slightly. Macronucleus spherical. 

 Undulating membrane small. Conti-actile vacuole single. Cuticular sur- 

 face longitudinally striated. 



Length of type specimen, 56 microns. (Fig. 23, plate XXXVII.) 



Genus Colpoda Mull. 



Body persistent in form, oval or reniform, compressed laterally, with 

 convex dorsal surface. Oral aperture in a deep depression a short dis- 

 tance from the anterior extremity. No undulating membrane, but a few 

 stronger cilia located at the posterior border of the mouth. Pharynx 

 absent or inconspicuous. Surface longitudinally sti-iated. Cilia very 

 fine. Resembles Colpidium very closely, but differs in the motor ap- 

 paratus connected with the mouth. 



Colpoda cucullus Ehr. 



Body reniform, about one and a half times as long as broad. Posterior 

 end broad and bluntly rounded; anterior end narrower and less bluntly 

 rounded. Body curved toward the ventral side. Striations conspicuous 

 only at the extremities, and especially at the anterior extremity. Macro- 

 nucleus spherical, almost central in position. A single micronucleus. 

 Contractile vacuole single, posteriorly located. 



This is a very common form in infusions of hay and leaves. 



Length of type specimen, 95 microns. 



Colpoda helia Stokes. 



Body elongated reniform, rounded at both extremities. Anterior ex- 

 tremity slightly curved toward the ventral aspect. Mouth situated about 

 one-third the length of the body from the anterior end. Pharynx short. 

 Macronucleus ovoid, nearly central in position. Conti'actile vesicle in the 

 posterior half of the body. 



Length of type specimen, 175 microns. (Fig. 21, plate XXXVII.) 



Genus Tillina Gruber. 



Body bean-shaped, persistent in form. Mouth located near the middle 

 of the ventral side. Pharynx long and recurved. Cuticular surface 

 clothed with fine cilia. Longer cilia bordering the mouth and continued 

 down the pharynx. Macronucleus large, oval. Contractile vesicle single, 

 postero-terminal. 



I have taken my classification of this genus from Miss Louise Hoyt 

 Gregory, who, in her article on The Life History of Tillina magna, places 

 it in the family Chiliferida?. 



