PLATE III". 



Echiuothrix calamaria, /. 1, 2. 



1. Seen IVoin the iibaetiiial pule. 



2. Seen in profile. 



Echinothrix turcarum, /. S. 



3. Seen from the abactiual pole. 



Astropyga pulvinata, /. J^. 



4. Seen from the abactinal pole. 



I^All Figs, two thirds natural si:x.) 



