ORGANS OF DIGESTION. V2 1 



and broken shells, often swallowed with the food and found 

 distending the stomach, are thrown out by the same oral 

 aperture when the stomach is protruded. The margins of 

 the oral disk, supporting the tentacula, are sometimes found 

 extended in foliaceous expansions, and covered with minuter 

 forms of these sensitive organs, by which the prehensile and 

 respiratory surfaces are also increased in extent. In others 

 the tentacula aie tuberculated on the surface, or are length- 

 ened and ramified with the luxuriance of many inferior 

 alcyonia, or like the roots of a rhizostoma, or the radiating 

 divisions .of a euryale, as we see in the actinia alcyonoidea 

 (Fig. 112. A. C.) and the actinia arborea (Fig. 112. B. D.), 



FIG. 112. 



two large species from the South Pacific. The cylindrical 

 body of the actinia alcyonoidea (112. A.) striated longitu- 

 dinally with numerous undulating brown-coloured bands, 

 terminates above in a circular green disk spotted with 

 deeper shades of the same hue, and presenting a lively rose- 

 coloured oral aperture in the centre. From the outer margin 

 of the disk sixteen large cylindrical ramified tentacula extend 

 to the distance of half-a-foot from the mouth, and have all 

 their divisions terminated by rasemose enlargements (112. 

 C.) which are closely covered with minute pedunculated 

 suckers (112. C. b. c.), by which the sensitive, the prehen- 

 sile, and the respiratory surface of this remarkable zoophyte 

 is greatly increased, and it is better enabled to perceive and 

 to grasp larger prey floating or swimming freely through the 



PART III. Y 



