Plate XV. 



Fig. I. Ambiilacral area of Echinus esculentus. '/i. 



— 2. luterambulacral area of Echinus acutiiSy var. norvegicns. ^/i. 



— 3. — — - — affinis. ^/i. 



— 4. — — - — elegans. ^ i. 



— 5. — — - — esctilcnhis. '/i. 



— 6. Apical area of Parechiuns miliaris. ^/,. 



7. Ambulacral area of Parechinus iniiiaris. 





— 8. — — - — microtnbercnlatiis. ^/i. 



— 9. Interanibulacral area of Parechinus microtuberculatus. ^/i. 



— 10. Ambulacral area of Echinus aff^inis. ^ /i (young specimen). 



— II. Interanibulacral area of Parechimis miliaris. ^/V 



— 12. Apical area of Parechinus microtuberculatus. ^/,. 



— 13. Ambulacral area of Echinus Alexandri. ^/i. 



— 14. — — - — acutus., var. mediterranea. '/i. 



— 15. Interanibulacral area of Echinus acutus., var. mediterranea. Vi- 



— 16. Ambulacral area of Echinus acutus^ var. norvegicus. ^/i. 



— 17. Interanibulacral area of Echinus Alexandri. 2/,. 



