218 ZOOLOGY. 
similis, lives in brackish water, according to Claus. Sup- 
posed plates of Holothurians have been found in the 
Jurassic rocks. 
Cuiass IV.—HOLOTHUROIDEA. 
Worm-like, cylindrical Echinoderms, with a muscular body-wall usually 
containing calearevus bodies ; with a circle of branched tentacles, a terminal 
opening of the intestine, madreporic plate internal, and usually a res- 
piratory cecal appendage. Unisexual or bisexual, developing by a metamor- 
phosis from cylindrical, auriculated, free-swimming larve; or ametabolous, 
Order 1, Apoda.—No ambulacral feet. Family 1. Synaptide (Eupyrgus, 
Chirodota, Synapta). Family 2. Molpadide (Caudina, Mol- 
padia). 
Order 2, Pedata.—Respiratory tree present, and the ambulacral feet. 
Bisexual. Family 1. Dendrochirote (Thyone, Psolis, Echi- 
nocucumis, Pentacta), Family 2. Aspidochirote (Holothu- 
ria). The Hlasipoda are a group of deep-sea forms. 
TABULAR VIEW OF THE CLASSES AND ORDERS OF ECHINODERMATA, 
Pedata. 
(olothuria.) 
Apoda. 
(Chirodota.) 
Autechinida. 
—~——__ (Echinus.) 
HOLOTHUROIDEA. Palechinida, 
(Melonites.) 
EcHINOIDEA. 
Asteridea. 
(Asterias.) 
Ophiuridea, 
(Ophiura.) 
Brachiata. 
H+ (Encrinus.) 
ASTEROIDEA. 
Cystidea. 
(Spheronites.) 
Blastoidea, 
ca ane 
_—,—— 
CRINOIDEA. 
—_ nil 
ECHINODERMATA. 
