ERYLUS CALICULATUS. 315 



reniform shape, and the small size of its aspidasters. It is nearest allied to 

 Eryliis rotundus. From this E. caliculutus is distinguished by the shape, which 

 is massive lobose to digitate in E. rotundus and caliculate in E. caliculatus; 

 by the microrhabds, which are amphiox in the former and amplaistrongyle in 

 the latter; by the aspidasters which are absolutely smaller, relatively thinner, 

 and oval or circular in E. rotundus and absolutely larger, relatively thicker, and 

 in part also reniform in E. caliculatus; and by the spicules generally which are 

 smaller and much less robust in E. rotundus than in E. caliculatus. 



