CORALLIFERI. 519 



S^jj^^^l 



soft, gelatinous, and completely covered with rosettes of tentacula which 

 are the Polypi or rather the Actiniae, for they usually have several circles 

 of tentacula, and the lamellae of the stars correspond in some respects to the 

 membranous laminae of the body of the Actiniae. The bark and Polypi 

 contract on the slightest touch. 



MILLEPORA, Lin. 



Here the stony portion is extremely various in form, and the surface 

 merely marked with little holes or pores, or even without any apparent ori- 

 fices. 



In the third tribe, or the NATANTES, the axis is stony but not 

 fixed. 



PENNATULA, Lin. 



A common body, free from all adhesion, of a regular and constant form, 

 and susceptible of locomotion by the contractions of its fleshy portion and 

 ' the combined action of its Polypi. This body is fleshy, and contracts or 

 dilates in its various parts by means of the fibrous layers that enter into its 

 composition; its axis encloses a simple stony stem; the Polypi have gene- 

 rally eight dentated arms. Most of the species diffuse a vivid phospho- 

 rescent light. 



The Pennatulx, properly so called, have given their name to the whole 

 genus, which name has been derived from their own resemblance to a 

 quill. The portion destitute of Polypi is cylindrical, and terminates in an 

 obtuse point. The other part is furnished on each side with wings or 

 laminae, more or less long and broad, supported by spines or rigid setae 

 which arise from their interior and roughen one of their edges, without, 

 however, being articulated with the stony stem of the axis; it is from be- 

 tween their laminae that the Polypi protrude.;! 



Small, porous and stony bodies, which nuturalists have thought 

 may be approximated to the Millepora, are found among fossils and 

 in the ocean. If they were enveloped by a rind of bark containing 

 Polypi, they would be movable Coralliferi, and should rather be 

 placed near the Pennatulae. Such are the 



OVTJLITES, Lam., which have the form of eggs, hollow, and frequently 

 perforated at both ends: the LTJNUIITES, which are orbicular, convex, stri- 

 ated, and porous on one side, and concave on the other: and the OHBUUTES, 

 that are orbicular, flat, or concave, 'porous on both sides or on the edges. 

 If the DACTYLOPORA be free, as in the opinion of Lamarck, it will also be- 

 long to this subdivision; it is a hollow ovoid, open at both ends, and with 

 two envelopes, both perforated by meshes like the Retepora. 



