BRACHIONUS 85 



muscular apparatus provided with three chitinous trophi (a 

 median incus and two mallei). It is used in grinding the 

 food. The grinding movements are easily seen. A very short 

 gullet leads from the mastax to the large stomach. The in- 

 testine is short and thick and opens into a cloaca. The anus 

 is near the base of the tail, on the dorsal surface. 



4. The reproductive and excretory systems are not easily 

 seen. An ovary and a large vitellarium are present. The 

 oviduct opens into the cloaca. Two long nephridial tubes 

 open into a contractile vesicle that in turn opens into the 

 cloaca. 



5. There is a single ganglion in the anterior dorsal region, 

 immediately beneath two red eye spots. Anterior to the eye 

 spots is a dorsal feeler, which is a tactile organ. 



There are many common rotifers that have no lorica and 

 some of them have the trochal disk two-lobed. 



Jennings: Rotatoria of the United States with Especial Reference to 



those of the Great Lakes. Bull. U. S. Fish Com., 19, 1899. 

 Whitney: The Desiccation of Rotifers. Am. Nat., 42, 1908. 



