Plate 33. 

 1-3. ColobocentrotuB Stimpsoiii A. Ag. 



1. Seen from the actinal side. 



2. Seen from the abactinal side. 



3. The same specimen, seen in profile, facing the odd anterior ambulacrum. 



The odd anterior ambulacrum occupies the center of the upper part of figures 1, 2. 



All figures are natural size. 



Bonin Ids., Captains Einggold and Rodgers, N. P. Ex. Ex., Dr. Wm. Stimpson Coll. 



