BRITISH ZOOPHYTES. 207 



and depress the epistome in the PhylacfoJoemata, and 

 those which are scattered about the various portions 

 of the polypide to aid in the processes of digestion. 

 The cavity of the zooecium, in which the alimentary 

 canal is suspended, is called the perigastric cavitf. 

 This is always filled with fluid, in which float a number 

 of particles which have been detached from the cells of 

 the endosarc, and into which the spermatozoa are dis- 

 charged. In this cavity the reproductive organs are 

 lodged, and the ova pass through their stages into the 

 larval forms. The fluid of the perigastric cavity 

 appears to consist of water and the products of diges- 

 tion, the latter evidently transuding through the walls 

 of the stomach. The tentacles being hollow, this fluid 

 circulates into them, and is there aerated, this process 

 being analogous to the aeration of the blood of higher 

 animals, to which the fluid with its contained cor- 

 puscles or particles bears no slight resemblance. 



Connecting the base of the stomach with the endo- 

 cyst of the zooecium is a contractile cord called the 

 funiculus, which plays a very important part in the 

 economy of the animal. The funiculus extends some 

 distance along the wall of the stomach, and gives ofl" 

 processes which reach to the side of the zooecium. 

 The funiculus consists of elongated cells pointed at 

 both ends, and resembling in shape the frustules of 

 Navicula. It extends through the base of the zooecium 

 into the one adjoining it, and so forms a connection 

 between the zooecia of a colony. This funiculus is 

 pometimes called the endosarc. It has been considered 

 by Mliller that the funiculus was a " colonial nervous 

 system ;" but this view is not generally accepted. It 

 is found in both mai'ine and fresh-water species, and 



