268 ZOOLOGY. 



11. Tuhularia. Stem tubular, simple or branched, fixed by 

 the base ; animal proceeding from the extremity of the 

 tube, and having its head crested with tentacula. 



12. Corallina. Coralline. Animal in form of a plant ; 

 stem fixed, with calcareous subdivided branches, mostly 

 jointed. 



13. Sertularia. Animal as the last ; stem branched, pro- 

 ' ducing polypes from minute cup-shaped cells. Of this 



genus there are two families ; * stern horny, tubular, 

 afiixed by the base, and furnished with vesicles or ova- 

 ries containing polypes^ ^SS^j <"■" lining young ; ** 

 stem crustaceous, inclining to stone, composed of 

 rows of cells j vesicles wanting, in lieu of which are 

 small globules. 



14. Pennatula. Sea-Pen. Animal not affixed, of various 



shapes, supported internally by a bony substance, naked 

 at the base, the upper part with lateral ramifications ; 

 furnished with rows of tubular denticles^ producing 

 radiate polypes from each tube. 



15. Hydra. Poltpe. Animal afiixing itself by its base, 



linear, gelatinous, naked, contractile, and furnished 

 with setaceous tentacula^ inhabiting fresh waters, and 

 producing its deciduous offspring from its sides. 



