PuaTE 39. 
1-2. Colobocentrotus Mertensii Brandt. 
1. Showing the right posterior ambulacrum, with the right posterior interambulacrum, 
and a part of the right anterior ambulacrum. 
2. Showing the odd posterior interambulacrum with the bivium, and half of the right 
posterior ambulacrum. 
3-4. Colobocentrotus Stimpsoni A. Ag. 
3. The right posterior interambulacrum, with the right posterior ambulacrum and a part 
of the right anterior ambulacrum. 
4. The right anterior interambulacrum, with the right anterior ambulacrum and a part of 
the odd anterior ambulacrum. 
1-2 are from a specimen of 70 mm. in diameter, and 3-4 from a specimen measuring 
88 mm. in diameter, including the spines. The dotted lines join the radioles of the same 
vertical row. 
Bonin Ids., N. P. Ex. Ex., Dr. Wm. Stimpson Coll. 
