TABLE OF CONTENTS. 



Page. 



Introduction 1 



Description of species 2 



Calocidaris niicans (Mortensen) 2 



Tretocidaris bartletti (A. Agassiz) 5 



Stylocidaris lineata, new species 10 



Cidaris abyssicola, var. terotispina, new variety 13 



Cidaris rugosa (H. L. Clark) 16 



Araeosoma belli Mortensen 17 



Diadema antillarum Philippi 21 



Revised list of the Echinoids known to occur in the American region of the North Atlantic, and 



in the West Indies 1'2 



Explanation of plates _ 26 



Index 29 



V 



