POLYMASTIGINA 



263 



Family 2 Tetramitidae Biitschli 



With 4 flagella, no one of which undulates on body surface. 



Genus Tetramitus Perty. Ellipsoidal or pyriform; free-swim- 

 ming; cytostome at anterior end; 4 flagella unequal in length; a 

 contractile vacuole; holozoic; fresh or salt water. 



T. rostratus P. (Fig. 123, a). Form variable; usually ovoid with 

 narrow posterior region; 18-30/x by 8-1 1/z; stagnant water. Bunt- 

 ing (1922, 1926) observed a very interesting life-cycle of an 

 organism which she found in culture of caecal contents of rat 

 and which she identified as T. rostratus (Fig. 122). 



Fig. 123. a, Tetramitus rostratus, X620 (Lemmermann); b, T. pyri- 

 f or mis, X670 (Klebs); c, T. salinus, X1630 (Kirby); d, Collodictyon 

 triciliatimi , X400 (Carter): e-j, Costia necatrix (e, f, X800 (Weltner); 

 g-i, X1400 (Moroff); j, two individuals attached to host integument 

 X500 (Kudo)); k, Tricercomonas intestinalis, X1730 (Wenyon and 

 O'Connor); 1, Coproviastix prowazeki, X1070 (Aragao). 



T. pyriformis Klebs (Fig. 123, h). Pyriform, with pointed pos- 

 terior end; 11-13^ by 10-12^i; stagnant water. 



T. salinus (Entz) (Fig. 123, c). 2 anterior flagella, 2 long trailing 

 flagella; nucleus anterior; cytostome anterior to nucleus; a 



