ORGANS OF DIGESTION. 



317 



are seen numerous conical tubular fleshy tentacula, like the tu- 

 bular feet of a holothuria. In the still deeper and more isolated 

 concavities of the pavonice are found the large depressed ex- 

 panded polypi, with eight-lobed orifices, and closely re- 

 sembling the sea-anemonies in their exterior form and 

 internal structure, as seen in the deep-green polypi of the 



FIG. 110. 





pavonia lactuca (Fig. 110. a. .), from the shores of the 

 South Sea Islands. The transparent, common, connecting, 

 fleshy substance of these polypi, becomes a thin arid almost 

 imperceptible layer at its exterior margins, but rises, in the 

 expanded condition of the animal, even beyond the extreme 

 edges of the delicate calcareous foliated expansions (110. c.) 

 which compose this elegant lithophyte, and thus extend their 

 limits by the addition of calcareous matter. The eight short 

 lobes (110. b.) of the oblong oral disc of these broad depressed 

 N polypi (110. a. .), are the only traces of marginal tentacula 

 which they present. The cavities containing the polypi are 

 almost destitute of those vertical prominent sharp ridges 

 and depressions, which mark both surfaces of the undulating 



