INFUSORIA 



55 



end and an undulating membrane in the gullet: 3 species; in fresh 

 and salt water. 



F. leucas Ehr. (Fig. 86). Body brown or black in color; length 

 .3 mm. or more; a furrow extends back from the mouth: in fresh and 

 salt water; Woods Hole. 



2. COLPIDIUM Stein. Body oval, the ventral side being incurved 

 and the forward end smaller than the hinder; mouth central: 2 species; 

 in fresh and salt water. 



C. colpoda (Ehrenberg) (Fig. 87). Length .045 mm. or more: in 

 fresh and salt water; common in infusions; Woods Hole. 



3. URONEMA Dujardin. Body minute and oval, with a long bristle 

 at the hinder end; mouth near middle surrounded by membranes: 6 

 species; in fresh and salt water. 



Fig. 87 



Fig. 88 



Fig. 89 



Fig. 87 Colpidium colpoda (Calkins). Fig. 88 Uronema marinum (Calkins). 

 Fig. 89 Colpoda cucullus (Conn). 



U. marinum Duj. (Fig. 88). Length .05 mm.: in fresh and salt 

 water; in decaying vegetation; marine; Woods Hole. 



4. COLPODA 0. F. Miiller. Body laterally compressed, with rounded 

 dorsal and straight ventral surface; mouth toward forward end, sur- 

 rounded by long cilia: several species; in fresh water, especially in hay 

 infusions. 



C. cucullus Mill. (Fig. 89). Body ellipsoidal; length .1 mm.: in 

 fresh water; very common. 



FAMILY 5. UKOCENTBIDAE. 



Body barrel-shaped; mouth near the middle; a broad girdle of 

 longer cilia around the body: 1 genus. 



UROCENTRUM Nitzsch. Characters as above : 1 species ; in fresh and 

 salt water. 



U. turbo (0. F. Miiller) (Fig. 90). Length .06 mm.; swims with a 

 whirling motion. 



FAMILY 6. PAEAMECIIDAE. 



Body elongate, with a long, deep, oral groove leading to the mouth 

 which is in the middle or hinder part of the body: 1 genus; common in 

 infusions and decaying organic matter. 



