OBSERVATIONS ON THYONE BRIAREUS. 2/1 



Thyone's food consists of the microscopic organisms and debris 

 to which the tips of the branching tentacles adhere. Such ma- 

 terials are wiped off as the tentacles are thrust into the mouth 

 and extended again. The stomachs of seven freshly collected 

 individuals were examined on August lo and found to contain : 

 living protozoans {LicJinopliora, Gyninodiniuvi), nematodes and 

 diatoms (several species) ; filamentous and unicellular algae ; 

 pieces of plant tissue ; encysted protozoans ; two harpacticid 

 copepods ; and an ostracod. TJiyone is apparently a rather indis- 

 criminate feeder but sand was infrequent in the stomach contents 

 and, though particles of sand were seen sticking to the tentacles 

 as they entered the mouth, most of them were brought out again 

 as the tentacles emerged. 



VI. Respiratory Movements. 



Thyone carries on a regular system of breathing movements by 



which water is taken into the cloacal chamber and expelled 



again. The general plan of this chamber is shown in median 



longitudinal section in Fig. 4. There are three openings from 



1- -w^ 



Fig. 4. Diagram representing a median longitudinal section through the posterior 

 end of the body, a, integument ; b, sphincter muscle ; c, cloacal chamber ; i, intes- 

 tine ; /, longitudinal body muscle ; m, circular body muscles ; r, radial muscles ; t, 

 respiratory trees. /, opening into cloacal chamber ; 2, opening into respiratory 

 trees ; j, opening from intestine. 



the cloacal chamber c. These lead to the exterior /, to the 

 respiratory trees 2, and to the intestine j. During respiration 

 the opening from the intestine j into the cloaca usually remains 

 closed and takes no part in the breathing movements. Water is 



