96 DAVENPORT ACADEMY OF SCIENCES. 



Gyrocoris oxyura Stein. 



Possessing the characters of the genus. Tail-Hke process with 

 a broad base and even exceeding the bodj^ in length. Nucleus 

 moniliform, short, usually compo.sed of three bead-like masses 

 united, and transversely placed, in the posterior region. Con- 

 tractile vesicle also posterior. 



Length, including caudal process, 1 10-150 microns. (Fig. 157, 

 PI. XXI.) 



A rare species in this state, but found in Johnson county in 

 pond water among decaying plants. The organism moves swiftly, 

 rotating on its longitudinal axis. 



Conjugation has often been observed to take place, the ventral 

 surfaces of the conjugants being united. 



Family, HALTERHD^. 



HALTERIA Dujardin. 



Spheroidal, with a spiral wreath of large cilia about the anterior 

 border. Oral aperture eccentric, on the anterior margin, the 

 equatorial region bearing a circle of long, fine, springing setae. 



Halteria grandinella Miill. 



Body usually somewhat spherical, truncate anteriorly, broadly 

 or acutely rounded posteriorly. Body without cilia except the 

 anterior wreath and the equatorial circle of springing-hairs. 

 Nucleus oval or round, centrally located. Contractile vesicle near 

 the nucleus. lindoplasm transparent. 



Length of body, 25 microns. (Fig. 158, PI. XXL) 



Halteria grandi)ieUa moves by a rotary motion on its longitu- 

 dinal axis accompanied by frequent sudden leaps, which are said 

 to be due to the reflex of the fine springing setae. 



The species is common to pond water and is widely distributed. 

 It has also been found in great quantities in spring water among 

 algae. 



Order, HYPOTRICHA. 



Family, OXYTRICHID^. 



UROSTYLA, Ehrenberg. 



Elongate-oval, very flexible. Frontal styles three or more, 

 anal styles from five to twelve, slender and in an oblique row. 



