148 THE OCEAN WORLD. 



prodigious, of animals such as the crustaceans, worms, and small fishes. 

 They are all marine, nearly all attached to the same spot for life, and 

 they live in colonies. Some few are isolated and live by themselves, 

 either free or attached to the soil. They differ altogether from the 

 animals belonging to the Alcyonaria by their disposal of, and mode of 

 multiplying, tentacula. These appendages in the Zoantharia never 

 present the lipinnate arrangement which is observable in the Alcy- 

 onaria. They are habitually simple, and, if they present ramifications, 

 these are only exceptional. In nearly every instance, the tentacles 

 exist to the number of twelve, eighteen, twenty-four, and even larger 

 numbers, which form a sort of concentric crown to the animal. 



Zoantha thalassanthos (Lesson), which has given its name to the 

 group, consists of large turf-like tufts of coral attached to a rock. Its 

 animalcules are packed closely together, and their expanded flower- 

 like heads have a curious resemblance to a mass of flowers in full bloom. 

 They are borne on bending root-like stems of pure white, interlacing 

 one with the other, surmounted by a fusiform or spindle-shaped body, 

 pediculate and swelling towards the middle, but truncate at the 

 summit, of a reddish-brown colour, marked with longitudinal stripes 

 more highly coloured; its consistence is firm and parchment-like. 

 From the body issues a tube, narrow, muscular, contractile, and red in 

 colour, terminating at the summit in eight elongated arms or tentacula, 

 of a pure yellow, traversed by a nervure of the same colour. The 

 edges of these arms are fringed with fine pinnae, parallel to each 

 other, of a bright maroon colour, and resembling the barbs of a 

 feather. According to Lesson, the arms of this Zoantha are kept un- 

 ceasingly in motion, which produces in the water small oscillating 

 currents, in the course of which the animalcules on which the polyps 

 feed are precipitated into the stream leading to their mouths. 



The tendency to produce a calcareous polypidom is a property almost 

 universal with animals of this class. Zoologists are agreed in dividing 

 them into three very distinct orders namely, the ANTIPATHID^I, con- 

 sisting of the genera Antipathes, Cirripathes, and Seipathes, in 

 which the polypidom is of a horny consistence ; the MADREPORID^E, in 

 which the polypidom is calcareous and stony ; finally, the ACTINHXE, 

 which produce no polypidom. 



