114 THE TUBIPOEA. 



margins of the extended membrane of each polyp 

 meet and coalesce. This being effected, the polyp 

 increases, and the lining tissue rising, continues the 

 cone-like orifice of the tube. From the base of the 

 arms extend eight filaments, running through the 

 tube, and attached to its lining membrane. On 

 these the germs of the future race are attached by 

 a neck or stalk, like minute eggs. How they are 

 expelled, whether during the polyp's life or not, 

 and how they cluster together and form bundles of 

 pipes upon the old ones, or in new situations, are 

 points utterly unknown. The limestone rocks of 

 Derbyshire abound with fossils of this creature. 



ALCYONIUM WITH POLYPS. 



Distinct from the polyps now considered are 

 those in which a tough body, often with calcareous 



