136 



ZOOLOGY. 



similis, lives in brackish water, according to Claus. 

 posed plates of Holothurians have been found 

 Jurassic rocks. 



m 



Sup- 

 the 



Class IV.— HOLOTHUROIDEA. 



Worm-like, eylmdrical Echinoderms, with a muscula/r hody-waU iisuaUy 

 containing calea/reous bodies ; with a circle of branched tentacles, a terminal 

 opening of the intestine, madreporic plate internaZ, and usually a res- 

 piratory coBcal appendage. Unisexual or bisexual, developing by a metamor- 

 phosis from cylindrical, auricu lated, free-swimming Iwrvm; or ametabokma. 



Order 1. Apoda. — No ambulacral f eet. Family 1. 8ynaptid(B(Et\\yjrga&, 

 Chirodota, Synapta). Family 3. Molpadidoe (Caudina, Mol- 

 padia). 



Order 2. Pedata. — Respiratory tree present, and the ambulacral feet. 

 Bisexual. Family 1. Dendrochvrotm (Thyone, Psolus, Echi- 

 nocucumis, Pentacta). Family 3. Aspidochirotm(Ro\othvi- 

 ria). The Elasipoda are a group of deep-sea forms. 



Tabular View of the Classes akd Orders of Echinodermata. 



Pedata. 

 (Holothuria.) 



Apoda. 

 (Chirodota.) 



HOLOTHUROIDEA. 



Autechinida. 

 (Echinue.) 



PalecMnida. 

 (Melonites.) 



ECHINOIDEA. 



Asteridea. 

 (Aeterias.) 



Ophiuridea. 

 (Opbiura.) 



ASTEROIDEA. 



Brachiata.. 

 (UncrinuB.) 



Oystidea. 

 (SpfiBeronites.) 



(Pentremltee.) 



CRINOroBA, 



ECHINODERMATA. 



