Plate VI. 



Fig. i. Stereocidaris ingolfiana, from above. 1 / I . 



— 2. — - the side. I / 1 . 



— 3. Test of Stereocidaris ingolfiana. Vi- 



— 4. Apical area of — 2 / x . 



— 5. Ambulacral-proeesses of Stereocidaris ingolfiana. I / I . 



— 6. — - Dorocidaris papillata. 1 / I . 



— 7. Interambulacral area - — I / z . 



— 8. Piece of ambulacral area of Dorocidaris papillata. ^/ z . 



— g. — - - Cidaris aj finis. 1 \. 



— 10. Interambulacral area of Cidaris affinis. 2 /' z . 



— n. Piece of ambulacral area of Stereocidaris ingolfiana. 4/ x . 



— 12. — - - Porocidaris purpurata. +/i- 



