EDMONDSON — PROTOZOA OF IOWA. 



95 



A form not uncommon to infusions of decaying vegetation is 

 referred conditionally to the above species. In most respects the 

 organism corresponds to the description of Steiitor rceselii although 

 a mucilaginous sheath has never definitely been made out for any 

 of the individuals observed in this state. The body is transparent 

 throughout the life-cycle, the nucleus is never moniliform, and 

 long .slender setae, which are retractile at will, often extend far 

 beyond the cilia of the general surface. 



The transparency of the organism together with the band-like 

 nucleus and well developed cuticular setae are specific characters 

 which, I believe, exclude the form from the species Stentor poly- 

 morph us or Siefitor cceuruletis. 



Reproduction is as represented by Figs. 154-156, PI. XXI, and 

 previously described under Steiitor ccsruleiis. Multiplication of 

 this species by means of internally produced embryos has been 

 reported by Claparede and Lachmann. 



Stentor polymorphus Miill. 



Characters correspond to those of Stentor cceruieus except that 

 the peripheral zone of the body is usually densely packed with 

 green chromatophores. 



Length, when extended, 500-1000 microns. 



Because of its general resemblance to Steiitor ccFruleus no figure 

 has been drawn of the species. The large size, green color, 

 together with the moniliform nature of the nucleus, will dis- 

 tinguish the species from other members of the genus. 



Stentor polymorphus may frequently be found in fresh water 

 among green alg;^:^ and in the late fall often collects in great masses 

 on the under side of rocks, in pools or small streams, where a 

 quiescent state is pa.ssed during the winter months. 



Reproduction commonly takes place by oblique fission. 



Family, GYROCORID.^. 

 GYROCORIS Stein. 



Anterior region helmet-shaped, rounded anteriorly, with a free 

 posterior region. Posterior region produced into a long, curved, 

 tail-like process. Oral aperture ventral in a ciliated groove. 

 Cilia extending from the mouth in a spiral across the anterior 

 border and around the free margin of the posterior region. 



