88 HALF AN HOUR WITH CORALLINES. 



much smaller than its predecessor, but is an 

 exquisitely beautiful object, the brown horny tubes 

 terminating in what seem bright yellow and red 

 flowers. 



The Sertularians are much commoner than 

 the species just mentioned, about twenty species 

 occurring in British seas, besides those of allied 

 genera. The horny envelope, which is all that is 

 left after these objects have been cast ashore and 

 dried, is called the " polypary." Its duty is to 

 enclose the common flesh of the colony (" ccenosarc "), 

 whilst it is prolonged to form a number of little cups, 

 called " hydrotheca." In these live the animals 

 proper, under the name of " polypites." They are 

 soft and retractile, and are provided with delicate 

 tentacles, capable of seizing and appropriating their 

 prey. The nutriment thus obtained by each 

 polypite serves more or less to support the entire 

 organism. In some respects they resemble the 

 Tubularians, in requiring special generative buds 

 for the purposes of reproduction. The Sertularians 

 are divided into five genera, of which only TTiuiaria 

 has the living animal or polypite imbedded in the 

 axis. Another has the cups confined to one side of 

 the axis (Hydrallmannia, or Plumularia)-, the remain- 

 ing three having two rows of cups or cells arranged 

 on each side the stem and branches. The student 

 will find no small degree of inconvenience in his 

 earlier attempts to thoroughly comprehend the 

 names of these common objects, on account of the 



