A Polyzoan. 49 



proximally directed pouch, the cozcum. The ccecum forms 

 the lower curve of the V. The intestine, richly ciliated, 

 extends from the coecum to the rectum ; the latter is often 

 better seen on the lower side of the zocecium. A loose 

 mass of non-muscular tissue, the funiculus, extends from 

 the lower end of the coecum to the deeper portion (prox- 

 imal) of the zooecium. Make a diagram of the digestive 

 tract. 



The Circulatory System. A vascular circulatory sys- 

 tem is not present in Polyzoa, though the fluid contained in 

 the body-cavity bears numerous cellular corpuscles. It 

 probably becomes purineri in the thin-walled, hollow tenta- 

 cles. 



The Muscular System. During life the lophophore, 

 together with the tentacles, is often forcibly retracted into 

 the cavity of the zocecium. This contraction is brought 

 about by the action of certain retractor muscles, which may 

 be seen in favorable specimens extending across the body 

 or ccelomic cavity from the inner surface of the zooecium to 

 the inner walls of the pharynx and lophophore. 



The Nervous System is represented by a supra-czsopha- 



geal ganglion, situated between the mouth and the anus. 

 From it certain nerves go to the tentacles. There are no 

 differentiated special sense-organs, and the entire system is 

 too difficult of demonstration to be considered in the present 

 course. 



The Reproductive System. The increase in the num- 

 ber of polypides in the colony, or zoarium, is brought about 

 asexually by " budding," though the more mature polypides 



