PLaTE 32. 
1-4. Colobocentrotus Stimpsoni A. Ag. 
1-8. Spheridia. 
1. Spheridia, the second measures 0.25 mm. in length; all the spheridia are from the 
right posterior ambulacrum. 
2. From the odd anterior ambulacrum, the first measures 0.26 mm. in length. 
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. 
~ 
5-8. Colobocentrotus Mertensii Brandt. 
5. Three spheridia 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. Spheridia 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 sphzridia 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. 
Bonin Ids., N. P. Ex. Ex., Dr. Wm. Stimpson Coll. 
