PLATE 28. 
1, 2. Dermatodiadema horridum A. Ag. 
1. Abactinal system of a specimen measuring 20 mm. in diameter with 7-8 primary 
tubercles; Station 3413. 
2, Abactinal system of another specimen of the same size as fig. 1, with smaller and more 
crowded anal plates; Station 3413. 
3, 4. Dermatodiadema globulosum A. Ag. 
3. Abactinal system of a specimen measuring 25 mm. in diameter ; Station 3398. 
4. Abactinal system of a specimen measuring 30 mm. in diameter; Station 3381. 
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