CLASS I. ECHINODERMATA. 



623 



The floor is of saud like the mountain drift 



And the pearl-shells spangle the flinty snow : 

 From coral rocks the sea-plants lift 



Their boughs when the tides and billows flow. 

 The water is calm and still below, 



For the winds and waves are absent there, 

 And the sands are bright as the stars that glow 



In the motionless fields of upper air : 

 There, with its waving blade of green. 



The sea-flag streams through the silent water, 

 And the crimson leaf of the dulse is seen 



To blush like a banner bathed in slaughter : 

 There, with a light and easy motion, 



The fan-coral sweeps through the clear deep sea ; 



And the yellow and scarlet tufts of ocean 



Are budding like corn on the upland lea; 

 And life, in rare and beautiful forms. 



Is sporting amid those bowers of stone, 

 And is safe when the wiathful spirit of storms 



Has made the top of the ocean his own. 

 And when the ship from his fury flies, 



When the myriad voices of ocean roar. 

 When the wind-god groans in the murky skies. 



And demons are waiting the wreck on shore — 

 Then far down in the peaceful sea. 



The purple mullet and gold-fish rove, 

 Where the waters murmur tranquilly 



Through the bending twigs of the coral grove." 



The Radiata — so called from their radiate form, and formerly denominated Zoophytes^ or Animal 

 Plants — are divided into five classes : Echinodermata, Sij^honophoj-a, Ctenopliora, Disco2)hora, and 

 Polypi. 



STAR-FISH : UNDER SIDE, SHOWING THE AMBULACRAL APERTURES. 



Class I. ECHINOKERIflATA. 



This term is derived from the Greek eckinos, a spine, and derma, skin ; the animals of this 

 class are distinguished for the structure of their skin, which generally presents a somewhat 

 leathery consistence. The different species vary greatly in their forms, though they usually 

 present a radiate arrangement in their parts. This system is conspicuous in the star-fishes, the 

 number five, in the distribution of the rays of these curious species, being more or less traceable in 

 the forms of nearly all those belonging to the class. Their organs of motion are similar, consisting of 

 a multitude of small feet called ambulacra, which are protruded through a number of perforations 

 left for this purpose in their calcareous coverings. The existence of a nervous system in these 

 animals is generally admitted by naturalists; they arc all furnished with distinct organs of diges- 

 tion and circulation, but it is doubtful if they possess organs of special senses. The sexes are 



