36 BUGULA TURRITA. 



Technical Note. Mount a small piece of a branch under a cover-glass 

 and study with the compound microscope. If details can not be 

 readily made out stain another branch with iodine, wash in water, 

 and mount in glycerine. 



c) The portion of the zooid which can be protruded from the mouth 



of the cup constitutes the introvert. 



d) A circular ridge flaring out slightly from the introvert is called the 



lophophore. This bears a number of ciliated tentacles. Count 

 the latter. 



e) Locate the mouth within the circle of tentacles. It opens into a 



pharynx which, in turn, narrows below to a short oesophagus. 



f) Follow the oesophagus to an enlargement in the central region of 



the body. This is the stomach. Below it ends in a blind sack, 

 or ccecum. 



g) From the upper end of the stomach trace the intestine to its termi- 



nus in the anus, located on the introvert just outside of the 

 lophophore. The distal portion of the intestine forms the thick- 

 walled rectum. 



h) The ccecum is attached to the bottom of the cuticular cup by a 

 band of threads called the funiculus. If male reproductive 

 elements are present they will be found clustered about this band. 

 Ova develop in the same individual on the wall of the body cavity 

 near the ccecum. 



i) Retractor muscle fibers pass from the walls of the zooecium to the 

 pharynx. These serve to retract the introvert and tentacles 

 when the animal is disturbed. 



j) Attached to the wall of the zooecium in most of the individuals is 

 a queer appendage resembling the head of a bird. This avicu- 

 larium, in the living condition, has a movement of its own, 

 drawing back the head, opening the beak, and snapping it together 

 again at regular intervals. The function of this appendage is not 

 well understood. It may serve to keep off encrusting organisms 

 of a lower type of life and it may assist the zooid in securing food. 



