58 



FliOTOZOA 



Family 1. PLAGIOTOMIDAE. 



The oral groove extends from the forward end of the mouth, near 

 the middle of the body; adoral zone along the left side of the groove; 

 body elongate: G genera. 



Key to the genera of Plagiotomidae here described: 



fli Oral groove spiral 1. Metopus 



On Oral groove straight. 



&i Forward end acute and turned to the left 2. Blepharisma 



62 Body straight and worm-like 3. Spirostomum 



1. Metopus Claparede and Lachmann. Body eylin- 

 Wi drical; oral groove extends spirally across the forward 



two-thirds of body; contractile vacuole at hinder end: 

 2 species; in fresh and salt water. 



M. sigmoides (0. F. Mliller) (Fig. 97). 

 Length .13 mm.; body very contractile: in 

 fresh water. 



2. Blepharisma Perty. Forward end 

 acute and turned to the left; hinder end 

 rounded : several species ; in fresh water. 



B. undulans Stein (Fig. 98). Length 

 .37 mm.; color red: in fresh water. 



3. Spirostomtjm Ehrenberg. Body long, 

 and worm-like, very contractile, with dis- 



Fig. 97 



Metopus 



sigmoides 



(Conn). 



cylindrical, 

 tinct sjDiral 



Fig. 08 



Blepharisma 

 vnduluns 

 (Conn) , 



striations; nucleus bead-like; oral groove in 

 about first third of body; contractile 

 vacuole at hinder end: 2 species; in fresh 

 and salt Avater. 



S. teres Claparede and Lachmann 

 (Fig. 99). Length .4 mm.; body tapers 

 slightly at both ends; nucleus sometimes 

 simple. 



S. ambiguum (Bory de Vincent). Body 

 1 mm. long or more, and not tapering. 



Fig. 99 



Spirostomum 



teres 



(Conn). 



Family 2. BURSAEIIDAE. 



Body usually oval and flattened, the oral groove being a triangular 

 sunken area ending in the moutli; adoral zone on left edge of groove: 

 5 genera. 



Key to the genera of Bursariidac here described: 



fl, Animals parasitic 2. Balantidittm 



f/o Animals not parasitic. 



bi Body very broad 1. Bursaria 



62 Body cylindrical 3. Condylostoma 



