Plate 32. 



1-4. Colobocentrotus Stimpsoni A. Ag. 



1-8. Sphseridia. 



1. Spboeridia, the second measures 0.25 mm. in length ; all the sphaeridia are from the 



right posterior ambulacrum. 



2. From the odd anterior ambulacrum, the first measures 0.26 mm. in length. 



3. The second figure measures 0.27 mm. in length ; from the left anterior ambulacrum. 



4. From the left posterior ambulacrum, the first figure measures 0.22 mm. in length, the 



second 0.27 mm. 



6-8. Colobocentrotus Mertensii Brandt. 



5. Three sphseridia from the right posterior ambulacrum, the last one measuring 0.26 mm. 



in length. 



6. From the odd anterior ambulacrum, the first figure measures 0.27 mm. in length and 



the fourth one 0.23 mm. 



7. Sphseridia from the left anterior ambulacrum, the second figure measures 0.25 mm. in 



length. 



8. From the left posterior ambulacrum, the first figure measures 0.28 mm. in length. 

 The sphseridia of 1-4 are from the same specimen, 88 mm. in diameter, including the 



spines and those of 5-8 from an individual measuring 70 mm. 

 The enlargement of the figures is about the same. 

 Benin Ids., N. P. Ex. Ex., Dr. Wm. Stimpson Coll. 



