Plate I. 



Fig. 1. Chœtodiadema graniiliüiim; abactinal side; a little diminislied 



— 2. Plettrcchiniis siamcnsis ; abactinal side. From a specimen 8 mm. in diameter. 



— 3. Cluetucliudema yrdinilatiim: actinal side. Same specimen as Fig. 1. 



— 4. Pleurechinus maciilatus; side view. Nat. size. 



_ 5. — variegatus; — — From a specimen 12 mm. in diameter. 



— G. — — abactinal side. Same specimen as Fig. S. 



7. _ siamensis; — — From a specimen 12 mm. in diameter (from TorresStrait) 



— 8. — variegatus; — — Nat. size. 



_ 9. — Scillae; side view. From a specimen 8-5 mm. in diameter (from New Uritain). 

 jQ — — - — (from Mn.scat). 



— n. — siamensis; side view. Same specimen as Fig. 7. 



_ 12. — Döderleini; — — From a specimen 11 mm. in diameter. 



_ 13. — — abactinal side. Same specimen as Fig. 12. 



— 14. — maciilatus — — — — - — +• 



— 15. Opechiiuis spectabilis; — — Nat. size. 



— If), (iiinmecliiniis pidcliclttis; — — — - 



-17. I'lciirechiniis scilhv; - — Same specimen as Fig. 10. 



— 18. - - __--__- 9. 



— 19. — itariegatus; side view. Same specimen as Fig. 8. 



— 20. — siamensis; — — — — - — 2. 



— 21. Chœtodiadema yninulatum; actinal side. A little diminished. 



22. — — abactinal side. Same specimen as Fig. 21. 



— 23. Gymneclnniis inilclicltiis: side view. Same specimen as Fig. Ui. 



