18 SVEN LOVEN, ON A RECENT FOKM OF THE ECHINOCONID^.. 



PLATE II. 



Pygaster semisulcatus Phill. 



Fig. 11. The peristoraal part of the ambulacrum V, magnified. 



Fig. 12. Peristomal region seen from the interiör. 



Fig. 13. The two auricles of an ambulacrum. 



Fig. 14. Epistromal protuberances from the flanks of an interradium. 



