58 



PROTOZOA 



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: 6 genera. 



Key to the genera of Plagiotomidae here described : 



Oj Oral groove spiral 1. METOPUS 



a 2 Oral groove straight. 



&! Forward end acute and turned to the left 2. BLEPHABISMA 



6 2 Body straight and worm-like 3. SPIBOSTOMUM 



Fig. 97 



Metopus 



sigmoidea 



(Conn). 



cylindrical, 

 tinct spiral 



Fig. 98 



Blepharisma 

 vndulans 

 (Conn), 



1. METOPUS Claparede and Lachmann. 

 drical; oral groove extends spirally across 

 two-thirds of body; contractile vacuole at 

 2 species; in fresh and salt water. 



M. sigmoides (0. F. Muller) (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. SPIROSTOMTTM Ehrenberg. Body long, 

 and worm-like, very contractile, with dis- 

 striations; nucleus bead-like; oral groove in 



about first third of body; contractile 

 vacuole at hinder end: 2 species; in fresh 

 and salt water. 



S. teres Claparede and Laehmann 

 (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. 



Body cylin- 

 the forward 

 hinder end: 





Fig. 99 



Spirostomum 



teres 

 (Conn). 



FAMILY 2. BUESAEIIDAE. 



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

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

 5 genera. 



Key to the genera of Bursariidae here described : 



C4 Animals parasitic 2. BALANTIDIUM 



2 Animals not parasitic. 



&! Body very broad 1. BURSABIA 



& 2 Body cylindrical . .3. CONDYLOSTOMA 



