112 



THE AMERICAN MONTHLY 



[April 



as long as wide; plastic and changeable in shape; ven- 

 trum slightly concave anteriorly ; flagella originating 

 together at the anterior extremity , the anterior vibratile 

 flagellum nearly one half the body length ; this flagellum 

 is heavy strap-like and of uniform thickness from its ori- 

 gin to its distal end; the trailing flagellum from two to 

 two and a half times the body length ; contractile vesicle 



1. — Actinoinonas primus, x 900. 



2. — \itiiiomi);.as ii.UMinHdiate. st ■ . 



15. — .\ctinnmnnas. Hi'liir/,ii;iM 'lii. . 



4. — Heteromita ligulata. x llOll. 



5. — Petalomonas pusilla. x 2250. 



6. — Atractonema fusiforniis. x 1750. 



7. — Diplomastix rostrum, x 1400. 



8. — Diploniastix agilis. x 1200. 



9. — Diplomastix latero- ventral view. 

 10. — Anisonema disomato. x 1250. 

 11. — Auisonema. Transverse section. 



conspicuous and situated close to the anterior extremity; 

 nucleus round and located in the posterior body half ; 

 endoplasm, hyaline and slightly granular; locomotion 

 slow and equable while the anterior strap-like flagellum 

 is constantly and rapidly wagged. Size from 1-5000 to 

 1-3000 inch. 



Habitat — Ubiquitous. Transverse fission, 



