XVI 



PAGE 



B. ONTOGENY OF THE HOLOTHURIOIDEA 510 



C. ONTOGENY OF THE ECHINOIDEA . 519 



D. ONTOGENY OF THE ASTEROIDEA . 524 



E. ONTOGENY OF THE OPHIUROIDEA . 



F. ONTOGENY OF THE CRINOIDEA . 533 



XXII. PHYLOGENY . . 545 



Review of the most Important Literature . . . 551 



CHAPTER IX 



ENTEROPNEUSTA 



I. OUTER ORGANISATION ... ... 562 



II. THE BODY EPITHELIUM .... . 563 



III. THE NERVOUS SYSTEM . . . . 564 



IV. THE SENSORY ORGANS . .... 565 

 V. THE ALIMENTARY CANAL ...... 565 



VI. THE C(ELOMic SACS AND THE BODY MUSCULATURE. . . 571 



VII. THE "HEART VESICLE" 578 



VIII. THE LIMITING MEMBRANES, THE PROBOSCIDAL SKELETON, AND THE 



BRANCHIAL SKELETON ...... 579 



IX. THE BLOOD VASCULAR SYSTEM ..... 581 



X. THE GONADS ...... .585 



XI. ONTOGENY ........ 586 



XII. PHYLOGENY ........ 591 



Literature ........ 595 



APPENDAGE TO THE ENTEROPNEUSTA 



I. CEPHALODISCUS. ....... 596 



II. RHABDOPLEURA . .... 600 



Literature . < . . . . . .602 



INDEX . . 603 



