ECHINODERMATA 93 



circled with feathery tentacles. There are usually five 

 longitudinal rows of ambulacral suckers, but only three 

 are used for locomotion, of which one is more developed 

 than the rest. The mouth opens into a pharnyx lead- 

 ing to a long intestinal canal extending through the 

 body. Holothurians have the singular power of eject- 

 ing most of their internal organs, surviving for some 

 time the loss of these essential parts, and afterward 

 reproducing them. They occur on nearly every coast, 

 especially in tropical waters, where they sometimes 

 attain the length of three or four feet. As found dn the 

 beach after a storm, or when the tide is out, they are 

 leathery lumps, of a reddish, brownish, or yellowish 

 color. They may be likened to a sea urchin devoid of a 

 shell, and long drawn out, with the axis horizontal, 

 instead of vertical. They feed on small animals which 

 they catch with their tentacles, and upon organic par- 

 ticles from the sand. 



CLASS 5. Crinoidea 



The crinoids, or. "sea lilies," are fixed to the sea 

 bottom, temporarily or permanently, by means of a hol- 

 low, jointed, flexible stem. On the top of the stem is 

 the body proper, resembling a bud or expanded flower, 

 containing the digestive apparatus, and bearing the 

 branched arms. The mouth looks upward. There is a 

 complete skeleton for strength and support, the entire 

 animal body, arms, and stem consisting of thou- 

 sands of pieces embedded in the tissue of the body. 

 Crinoids were very abundant in the old geologic seas, 

 and many limestone strata were formed out of their 

 remains. They are now nearly extinct : dredging in the 

 deep parts of the oceans has brought to light a few living 

 representatives. Pentacrinus is permanently attached, 

 but the rosy, or feather star, is free during its adult life. 



