286 Education through Nature 



SOME CLASSES, ORDERS, AND GENERA OF ECHINODERMS. 



^. . ., ,. . . 7 f i. Order Brachiata, Pentacrinus 



i. Class Crmoidez radiate animals \ ^ O rder Blastoidea, P^mto 

 with jointed flexible stem j ^ Qrder Cystideaj Edriaster 



2. Class Asteroidea, star- 

 fishes with sucking 

 ambulacral feet 



i. Order Asteroidea, 

 true starfishes 



1. Asterias 



2. Ar chaster 



3. Solaster 

 .4. Cribella 



2. Order Ophiuroidea, 

 sand-stars and 

 brittle-stars 



1. Astrophyton 



2. Amphiura 



3. Ophioglypha 



4. Ophiocoma 



5. Ophiothela 



3. Class Echinoidea, 

 sea-urchins with 

 spherical or flat, 

 spiny body 



f i. Echinus 



.. , . ., 2. Arbacia 

 ,1. Order Antichimdaj 3> EcUnarachinus 



[4. Clypeaster 

 2. Order Spatangida, Hemiaster 



111 



i. Order Apoda, without 

 ambulacral feet 



Pentacta 

 ^ 



2. Order Pedata, w#& I 



ambulacral feet | ^ Aspidoch i rot ^ Holothuria 



