PuaTE 42, ; = 
1-8. Colobocentrotus Stimpsoni A. Ag. 
1. Interior view of the actinal side. 
2. One of the pairs of perforated plates of the buccal membrane, facing the odd anterior 
ambulacrum. 
3. Exterior view of the odd anterior ambulacral plates adjoining the actinal system. 
4. The same seen from the interior of the test. 
5. The tenth plate from the actinal system of the odd anterior ambulacrum. 
6. The same seen from the interior. 
7. Interior view of a plate of the right posterior ambulacrum at the ambitus. 
8. The ocular plate and the abactinal extremity of the left posterior ambulacrum, seen 
from the interior. 
In figures 3, 4, and 5, 6, a small cross shows the slanting perforation of the pore through 
the test. 
From a specimen measuring 88 mm. in diameter including the spines. 
Bonin Ids., Captains Ringgold and Rodgers, N. P. Ex. Ex., Dr. Wm. Stimpson Coll. 
