372 



PROTOZOOLOGY 



Fig. 155. Diagram illustrating the life-cycle of Tetramitus rostratus 

 (Bunting), a, cyst; b, vegetative amoeba; c, division; d, after division; 

 e, f, stages in transformation to flagellate form; g, fully formed flagel- 

 late; h, flagellate prior to division; i, flagellate after division; j-1, trans- 

 formation stages to amoeba. 



C. necatrix (Henneguy) (Fig. 156, e-j). 10-20ju by 5-10/x (Henne- 

 guy), 5-18/x by 2.5-7 fj. (Tavolga and Nigrelli, 1947) ; nucleus central; 

 uninucleate cyst, spherical, 7-10/iin diameter; when present in large 

 numbers, the epidermis of the fish appears to be covered by a whitish 

 coat. Davis (1943) found a similar organism which measured 9-14^ 

 by 5-8 m, on trout, Salmo irideus and Salvelinus fontinalis, and 

 named it Costia pyriformis. 



Genus Enteromonas da Fonseca (Tricercomonas Wenyon and 

 O'Connor). Spherical or pyriform, though plastic; 3 anterior flagella; 

 the fourth flagellum runs along the flattened body surface and ex- 

 tends a little freely at the posterior tip of body; nucleus anterior; 

 no cytostome; cyst ovoid and with 4 nuclei when mature; parasitic 



