502 



RADIATES .' ECHINODERMS. 

 Fig. 486. 



Mellita quinquefora, Ag. Tropical America. 



ganum, Rtimphia, Arach- 

 noides, Echinarachnius, 

 Dendraster, Lobophora, 

 Mellita, Encope, Rotula, 

 Echinodiscus, and Cly- 

 peaster, are the principal 

 ones. Clypeaster, Encope, 

 and Mellita are found on 

 the southeastern coast 

 of the United States; 

 Dendraster, at San Fran- 

 cisco ; Echinarachnius, 

 coast of New England 

 capepaimas. and northward. 

 CASSIDULID^:. This Family has the ambulacra peta- 

 loid, no jaws, peristome angular, central or subcentral. 

 Genera : Cassidulus, PygorJiynchus, Echinolampus, etc. 



SPATANGID.E. This Family contains echinoids which 

 are more or less depressed, heart-shaped, with the ambu- 

 lacra petaloid, and the peristome eccentric. They are 



