PLATE 41. 
1-7. Colobocentrotus Stimpsoni A. Ag. 
1. The left anterior interambulacrum. 
2. The ninth and tenth plates from the actinal system of the left anterior interambu- 
lacrum. B 
3. Showing the large tubercle of the fifth plate from the actinal system at the ambitus of 
the left posterior interambulacrum. 
The same, seen in profile. ‘ 
One of the primary interambulacral tubercles on the abactinal side. 
Grouping of the miliaries on the actinal side of the right posterior interambulacrum. 
Genital plate and pore of the left anterior interambulacrum. 
All the figures are from the same specimen, measuring 88 mm. in diameter, including the 
ue tn 
spines. 
Bonin Ids., Captains Ringgold and Rodgers, N. P. Ex. Ex., Dr. Wm. Stimpson Coll. 
