OPHIURIOIDS AND CRINOIDS. 



505 



Ophiocoma, Ophiarachna, OpJdacantha, Ophiopkolis, Opldo- 

 mastix, Ophiomyxa, Ophioscolcx, and Ophiothrix. 



The Euryalee are characterized by branched arms, and 



Fig. 490. 



Astrophyton Agassizii, Stimpson. Less than half the natural size. Northeast coast of 



North America. 



comprise the Genera Astcronyx, TricJiastcr, and Astrophyton. 

 Since the above was in type, we have seen the excel- 

 lent Catalogue of "Ophiuridae and Astrophytidas " by 

 Theodore Lyman, in which the list of genera is much 

 greater than that here given, and from which we learn 

 that more than a dozen genera of Ophiurans are found 

 on the coasts of the United States. 



SUB-SECTION V. 



THE ORDER OF CRINOIDS. 



THE Order of Crinoids embraces echinoderms which 

 are characterized by the great preponderance of the 



22 



