EDMONDSON — PROTOZOA OF IOWA. 67 



Length, with neck contracted, 50-70 microns. (Fig. 104, PI. 

 XIII.) 



A common and widely distributed species found in pond water. 

 Its swan-like appearance was suggested to the early observers by 

 its graceful movements, as it swims about extending its neck here 

 and there in search of food. 



Reproduction takes place by transverse fission. 



Family, TRACHELINID.^. 



AMPHII.EPTUS Ehrenberg. 



Elongate, usually flattened, with an anterior neck-like region at 

 the base of which is the oral aperture. Nuclei usually more than 

 one. Contractile vesicles single or numerous. Trichocysts some- 

 times present. 



Amphileptus meleagris Ehr. 



Body elongate, compressed, with a short, thick, neck-like 

 anterior region. Mouth, a cleft-like opening near the center of 

 the body. Nuclei, two in number, central in position. Contract- 

 ile vesicles numerous. No trichocysts. 



Length of body, 250 microns. (Fig. 105, PI. XIV.) 



Amphileptus mcIcagris has been found in pond water, also in run- 

 ning streams, although not an abundant species in this state. An 

 interesting phenomenon with reference to the life history of this 

 organism has been reported by various observers. After feeding 

 upon a zooid of Epistylis or some related species, AmpJiiltptus may 

 attach itself to the branch occupied by its victim and there become 

 encysted, during which period division into four animalcules 

 takes place. — Kent, "Manual of the Infusoria." Vol. II, p. 526. 



A curious relation between this species and Carc/icsinvi polypi- 

 mim which bears witness of the above phenomenon has come under 

 my observation. During September, 1905, on examining Car- 

 c/icsiujii polypiiiu))i taken from a small running stream near Iowa 

 City, numerous individuals of the species under consideration 

 were found attached to the branches of the peritrichous colony. 

 The posterior border of AniphUcptus was deeply cleft and clasped 

 the branch of its host; in addition a protoplasmic band from one 

 of the lip-like processes passed around the branch of Can/icsium, 

 thereby producing a firm anchorage. 



