5 1 * 



CCELENTERA TES. 



common trunk. The foot swells out like an onion and becomes transparent, 

 curves, and sinks into the stand ; and the stock, which during its period of 

 inactivity lay prone on the ground, assumes an erect position. In these sea-pens 



an alcyonarian coral, Alcyonium (nat. size). 



the parts of the stock may be compared with the parts of a feather, the whole 



being bilaterally symmetrical, and the single polyps being carried on the leaf-like 



ral appendages of the stem. The sexual animals, which are provided with all 



rgans necessary for a polyp, take in the food and reproduce themselves. The 



other less perfect brethren, called zooids, although more or less resembling these, 



