131 



CHAPTEE III. 



THE CLASS ACTIXOZOA. 

 Section I. 



MORPHOLOGY AND PHYSIOLOGY OF ACTINOZOA. 



1. Type of the Class: Actinia. — 2. General Morphology 3. Or- 

 gans of Nutrition. — 4. Prehensile apparatus. — 5. Tegumentary 

 Organs. — 6. Corallum or Skeleton. — 7. Muscular System and 

 Organs of Locomotion. — 8. Nervous System and Organs of Sense. 

 — 9. Reproductive Organs. 



I. Type of the Class: Actinia. — The -4c- 

 tinia, or Sea-anemone, is the type of the class 

 Actinozoa {fig. 26, c). 



The body of Actinia presents a soft^ fleshy, or 

 leathery consistence, and varies much both in 

 form and size, according as it assumes its con- 

 tracted or expanded condition. Average speci- 

 mens attain, when expanded, a diameter of from 

 one to three inches, their height being rather 

 less; but these dimensions are often exceeded. 

 The exips,ia.ded Actinia is somewhat cylindrical in 

 figure, attaching itself by one of its flattened ends, 

 known as the ' base,' a mouth being placed in the 

 centre of the ' disc,' or opposite extremity. Nu- 

 merous tentacles, disposed in alternate series, 

 surround the disc's outer margin, between which 

 and the mouth a region destitute of any append- 



K 2 



