THE FAUNA OF BOULDER COUNTY 245 



Family OPALINID^ 

 The form is oval and the body may be short or drawn out to resemble a worm. 

 They are characterized mainly by the absence of mouth and pharynx (Calkins). 



(74) Opalina Purkinje and Valentin. A species occurs with us, parasitic in the 

 frog (Ramaley). 



Order HETEROTRICHIDA 



With a usually uniform covering of ciha, and an "adoral zone," consisting of 

 short cilia fused together into membranelles. Edmondson gives this definition : 

 body entirely ciliate, cilia of the oral region longer than those of the general sur- 

 face and often fused together. However, in the suborder Oligotrichina the cilia 

 are limited to certain areas. 



Suborder Polytrichina 



With a uniform coating of cilia. 



Family PLAGIOTOMIDiE 



Mouth near or posterior to the middle of the body, preceded by a narrow peris- 

 tomal furrow (Edmondson). 



(75) Spirostomum Ehrenberg. Very long and narrow; one side of oral furrow 

 with larger ciha. 5. teres C. and L.* 



(76) Nyctotherus Leidy. We have a species parasitic in the frog (Ramaley). 



Family STENTORID^E 

 Large trumpet-shaped animals, the shape evidently suggesting the name Stentor. 



(77) Stentor Oken. S. ccernletis Ehrenberg*; blue, 250-300 m long. 



Suborder Oligotrichina 



Cilia limited to certain areas. 



Family HALTERIID^ 

 Body with an anterior ring of ciha, and in our genus a circle of long fine springing 

 hairs in the equatorial region. 



(78) Halteria Dujardin. Small, nearly spherical, with a leaping motion. 

 H. grandinella (Miiller).* 



Order HYPOTRICHIDA 



Usually flattened, with cilia confined to the ventral surface (Edmondson). Conn's 

 definition is: adoral zone wound to the left (to the right in Peritrichida) ; ventral 

 surfaces with characteristically arranged large cilia, while the dorsal surface carries 

 only five cilia or none. 



Family OXYTRICHID^ 

 Cilia of the central surface usually fused into styles or setae arranged in series. 



(79) Oxytricha Ehrenberg. Elongate, with three or more frontal styles and 

 several caudal styles. O. pelliondla (Miiller).* Length 80-100 ac. 



