94 HANDY BOOK OP 



converted, without any further remarkable changes, into 

 the permanent form. At birth, or on emerging into the 

 water, the only difference consists in the smaller number 

 of tentacles, and the partition wall of the cavity. 



The Lucernaria3, distinguished by a remarkable graceful- 

 ness of form, are closely allied to the Actinia?. The bell- 

 shaped body rises on a narrow stalk, which is usually found 

 attached to smaller marine plants on a rocky soil. The 

 tentacles are arranged, at regular intervals, in tufts round 

 the edge. The crystalline animal reflects green or red tints, 

 and can move with tolerable rapidity through the water, "by 

 alternate contraction and dilatation 



The Sea-pens, and other related varieties, such as the 

 Virgularise, Yeritellae, &c, seem capable of change of loca- 

 lity — they are composite, coralline polypes — which are not 

 firmly attached to the ground, but only have the stalk 

 thrust into the loose sand. The Sea-pens possess the faculty 

 of iridescence. If irritated at any place, the light flashes 

 from one branch and one polype to the other, till it reaches 

 the outermost point, while all the animals beneath the irri- 

 tated spot remain in darkness. If the Polypodum be thrown 

 into a vessel of sweet water, it emits sparks from every 

 branch, which produce a magnificent sight. 



These simple or gregarious families of Polypes, like all 

 those found in our waters, are insignificant when compared 

 with the reef-forming Corals of the hot zone. These are 

 propagated partly by producing small, simple, globular or 

 oval larvse, capable of independent movement by the posses- 

 sion of an external coat, which swim about for a period free, 

 till they attach themselves with one pole of their body, and 

 lay the foundation of a future Polyp colony. Partly, too, 

 they multiply themselves, like plants, by gemmation, and 

 form in this way numerous societies, whose individual 

 members are most closely connected. Each individual has 

 its special mouth and tentacles, and its own stomach ; but 

 it has no other specialties; for it is connected with its 



