44 COMPARATIVE ANATOMY AND PHYSIOLOGY. 



in the sea-pen (Pennatula) (Fig. 14 B), the tissue which 

 connects the polyps together is horny, in the noble red 



Fig. 14 c. Gorgonia fldbellum. 



coral it is calcified, while in the sea-fans (Gorgonia) an 

 elegant hard network is developed (Fig. 14 c). 



II. The Hexactinise ; the six tentacles or mul- 

 tiples of that number are filiform, and their edges 

 smooth. Some, like the common sea-anemone, 

 remain single throughout life, but, in most, buds are 

 given off, and a colony is formed. The deposition of 



