The SpH^ERiniA and 



(Aris 



COMPARATIVE ANATOMY 



(/) The Water Pores 



6. Blastoidea 

 («) The Ambulacral Skeleton 

 (b) The Stem . 



7. Cystidea 



D. The Spines and their Deria'atives- 



THE PEDICELLAEIiE 



E. The Masticatory Apparatus of the Echinoidea. 



totle's Lantern) ...... 



F. The Calcareous Rino of the Holothurioidea 



G. Further Deposits of Calcareous Matter 

 H. Concluding Remarks on the Skeleton 



III. The Outer Morphology of the Holothurioidea 



IV. The Position and Arrangement of the most Importan 



OrcxAns in the R.\Dn 



V. The Integument 



VI. The Water Vascular System 



A. The Madreporite and Stone Canal 



B. The Water Vascular Ring 



C. The Radial Canals, the Canals of 



Tube-feet, etc. . 

 The Ambulacral Appendages . 



D. 



VII. The Ccelom . 



A. The Body Cavity 



B. The Brachial Cavities . 



C. The Pericesophageal Sinus 



D. The Perianal Sinus 



E. The Axial Sinus . 



F. The Axial Organ 



G. The Chambered Sinus . 



VIII. The Pseudoh^mal System 

 IX. The Epineural System 

 X. The Blood Vascular or Lacunar System 



XI. The Nervous System .... 



A. The Superficial Oral System . 



B. The Deeper Oral Nervous System . 



C. The Apical or Aboral Nervous System 



D. The Third Nervous Sy.stem of the Crinoidea 



the Tentacles and 



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