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. CoLPiDlTJM 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 cucuUus (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 w^ater, especially in hay 

 infusions. 



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

 fresh water; verj^ common. 



Family 5. UEOCENTEIDAE. 



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

 longer cilia around the bodj' : 1 genus. 



Urocentrxtm 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. 



