434 THE AMERICAN NATURALIST [Vol. LIV 



to receive food, the corresponding portion of the lips 

 above is closed, to force it in. Fig. 10 shows diagram- 

 matically the relationship of the cycles of opening and 

 closing of the outer and inner lips. It will be noted that 

 once during each cycle (at its middle) both the outer and 

 inner lips correspond, for an instant, in attitude, the 

 same portions of each being in contact (Stage 3, Fig. 

 10). In some individuals the inner lips seemed not to 

 open and close at all, but appear to remain permanently 

 open. Observations on the motions of the lips were made 

 while the animals were incarcerated in very thick gela- 

 tine, and all of their movements much retarded. 



The ciliary action of the anterior portion of the body 

 can apparently be regulated according to the desires of 

 the animal and water currents, bearing food, can be 

 drawn toward the mouth either from directly in front of 

 the creature, from the side, or from behind (Figs. 11, 12, 

 and 13). 



Glaucoma feeds upon minute flagellates and other 

 minute protozoans, fragments of debris, tiny diatoms 

 and desmids, but the bulk of its food seems to consist of 

 bacteria. Fig. 14 shows what may frequently be ob- 

 served in a culture, i.e., a group of individuals clustered 

 about a mass composed mainly of bacteria, pressing 

 their lips against the substance, and urging portions of 

 it into the buccal cavity by the combined action of the 

 lips, and oral cilia. When feeding in this fashion the 

 movements of the outer lips resembles somewhat the 

 biting and chewing motions, of the mouths of the higher 

 animals. 



Curiously enough the complex development of the ex- 

 terior oral appendages seems to have no parallel within 

 the buccal cavity, since neither supporting pharyngeal 

 rods, nor even any definite pharynx, could be discerned. 



