136 



ZOOLOGY. 



similis, lives in brackish water, according to Glaus. Sup- 

 posed plates of Holothurians have been found in the 

 Jurassic rocks. 



CLASS IV. HOLOTHUROIDEA. 



Worm-like, cylindrical Ecfiinoderms, with a muscular body-wad uauaUy 

 containing calcareous bodies ; with a circle of branched tentacles, a terminal 

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

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

 phosis from cylindrical, auriculaled, free-sicimming larvae; or ametabolous. 



Order 1. Apoda. No ambulacral f eet. Family 1. <Sfypfecfe (Eupyrgus, 

 Cliirodota, Synapta). Family 2. Molpadidw (Caudina, Mol- 

 padia). 



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

 Bisexual. Family \. Dendrochirotw (Thyone, Psolus, Echi- 

 nocucumis, Pentacta). Family 2. Aspidochirotm (Sticbopus, 

 Holotkuria, Aspidochir). 



TABULAR VIEW OF THE CLASSES AND ORDERS OF ECHINODERMATA. 



Pedata. 

 (Holothuria.) 



Apoda. 

 (Chirodota.) 



HOLOTHUROIDEA. 



Autechinida. 

 (Echinus.) 



Palechinid,a. 

 (Melonites.) 



ECHINOIDEA. 



Asteridea. 

 (Asterias.) 



Ophiuridea. 

 (Ophiura.) 



ASTEROIDEA. 



Brachiata. 

 (Encrinns.) 



Cystidea. 

 (Sphaeronites.) 



Blastoidea. 

 (Pentremites.) 



I 



CRINOIDEA. 

 I 



ECHINODERMATA. 



