CONTENTS xv 



PAGE 



XII. THE SENSORY ORGANS ...... 462 



A. THE AMBULACRAL APPENDAGES AS SENSORY ORGANS . . 462 



B. NERVE ENDINGS IN THE INTEGUMENT .... 466 



C. AUDITORY ORGANS, ORGANS OF ORIENTATION . . . 468 



D. EYES ..... 468 



XIII. THE BODY MUSCULATURE ...... 470 



A. HOLOTHURIOIDEA ....... 471 



B. ECHINOIDEA ....... 471 



C. ASTEROIDEA ....... 472 



D. OPHIUROIDEA ....... 474 



E. CRINOIDEA ........ 474 



XIV. THE ALIMENTARY CANAL ...... 474 



A. GENERAL REVIEW ....... 474 



B. HOLOTHURIOIDEA ....... 476 



C. ECHINOIDEA ....... 479 



D. CRINOIDEA ........ 481 



E. ASTEROIDEA ....... 483 



F. OPHIUROIDEA . . . . . . . . 485 



XV. RESPIRATORY ORGANS ...... 485 



A. THE (INNER) RESPIRATORY TREES OF THE HOLOTHURIOIDEA . 487 



B. REVIEW OF THE RESPIRATORY ORGANS OF THE ECHINODER- 



MATA ........ 487 



XVI. THE CUVIERIAN ORGANS OF THE HOLOTHURIOIDEA . . 488 



XVII. EXCRETION ..... 489 



XVIII. THE SACCULI OF THE CRINOIDEA ..... 489 



XIX. GENITAL ORGANS ....... 490 



A. GENERAL MORPHOLOGY ...... 490 



B. HOLOTHURIOIDEA ....... 491 



C. ASTEROIDEA ....... 492 



D. OPHIUROIDEA .... . 494 



1. THE BURS.E ....... 494 



2. THE GENITAL APPARATUS ..... 495 



E. ECHINOIDEA ....... 498 



F. CRINOIDEA ..... 500 



G. ORIGIN OF THE SEXUAL PRODUCTS . . . 501 

 H. HERMAPHRODITISM IN ECHINODERMS . . 501 



1. CARE OF THE BROOD AND SEXUAL DIMORPHISM . 502 



XX. CAPACITY FOR REGENERATION AND ASEXUAL REPRODUCTION 504 



XXI. ONTOGENY ..... 506 



A. THE VARIOUS LARVAL FORMS OF THE ECHINODERMATA . 506 



