40 ZOOPHYTES. 



openings scattered over it, each of which is the centre of a slightly- 

 raised prominence. On expanding, these openings enlarge, the mar- 

 gin of each rolls back, and finally the whole mass, before seeming 

 lifeless, is covered with radiated disks, half an inch broad, having a 

 lilac centre, and bordered with a fringe of short tentacles. These are 

 the flower-animals — the polyps — of the Palythoa. They are repre- 

 sented of the natural size in figure 3. Some of the polyps on the 

 right are yet closed, while others are partly, and others wholly, ex- 

 panded. An enlarged view of the expanded polyp is shown in figure 

 3 a, exhibiting the circular disk — the fringe of short tumid tentacles, 

 in two series, one directed more upward than the other — and, upon 

 the disk, elevated greenish lines, extending, like radii, from each ten- 

 tacle to the convex centre in which the mouth is situated. The tex- 

 ture of the general mass of the zoophyte is peculiar, in consisting of 

 coral sand agglutinated by animal matter; particles of various colours 

 are here mingled. — white, red, and black. The sand, as it falls upon 

 the growing zoophyte, is enclo.sed by the slimy secretions of the sur- 

 face, and is finally introduced into its texture ; and thus firmness is 

 secured by calcareous granules from a foreign source. This is im- 

 perfectly represented in the figures 3 b and 3 c. 



31. The tentacles are naked — that is, without papillfe — ras in the 

 Actiniee, and each has a minute puncture at apex. These organs are 

 tubular, and they communicate internally with the visceral cavity 

 through a duct concealed under the radiated lines of the disk. The 

 mode of expansion by injection with water is the same as in the 

 animals above described. The mouth is without appendages of any 

 kind — a simple opening through the fleshy disk. 



32. The visceral cavity is cylindrical, and extends down below the 

 disk, into the polyp-mass, to its base. Its form and size, as com- 

 pared with the expanded animal, is shown in figure 3 a. The mouth 

 opens into this cavity, through an oblong stomach, which is about 

 one-fifth the length of the cavity, and is connected with its walls by a 

 series of radiating fleshy lamellae, as in the Actinia. There is also 

 another series of smaller lamelhe intermediate between these. The 

 stomach has a vertically striated or plaited structure within, and 

 closes at bottom at the will of the animal. Fisure 3 i is a vertical 

 section of the unexpanded polyp, through the mouth (opposite b') 

 and stomach [b' to c'), and the general visceral cavity ; and figure 

 3 (? is a transverse section, cutting across the oesophagus a little 



