IfJO THE VOYAGE OF H.M.S. CHALLENGER. 



Latmogone wyville-thomsoni, Theel. 

 Fig. 3. Deposits from the pseudhsemal vessels. 



Deimo validum, Theel. 

 4. Diagram exhibiting the relation of the dorsal and ventral surfaces and the posi- 

 tion of the processes and pedicels, a, dorsal surface ; b, ventral surface. 



Scotoplanes globosa, Theel. 



,, 5. View of the ambulacra! cavities of the pedicels, seen from the peritoneal cavity. 

 a, ambulacra! cavities ; b, one of the lateral ambulacra; c, openings into 

 the pedicels ; x, communication between the ambulacral cavities and the 

 ambulacra! canal. Natural size. 



„ G. View of the ambulacral cavities of the foremost pair of dorsal processes, seen 

 from the peritoneal cavity, a, ambulacral cavities ; b, the dorsal ambu- 

 lacra ; c, openings into the dorsal processes. Natural size. 



Deitna fastosum, Theel. 

 „ 7. Calcareous deposits from the system of fine canals which are in connection 

 with the minute papillae which surround the anterior aperture of the body. 



Oneirophanta mutabilis, Theel. 

 „ 8. A minute sheath with structureless contents and without any traces of 



calcareous deposits ; length about 0'08 mm. o, cells. 

 ,, 9. Slightly larger sheath without calcareous matters. 

 ,, 10. Sheath 0'20 mm. long, a, cells; b, the contents with traces of concentric 



structure at the centre of the sheath ; a, a minute calcareous body in the 



centre of the sheath. 

 „ 11. Another slightly larger sheath, c, calcareous bodies. All these four stages 



of development of spicula are taken from a very minute pedicel of a very 



young individual from Station 146. 



Ili/odcemon maculatus, Theel. 

 ,, 12. A later stage of development of a large wheel, seen from below. 

 „ 13. An early stage of development of a large wheel, seen from below. 

 „ 14. A slightly more advanced stage of development of a large wheel ; seen from 



below. 

 ,, 15. A fully developed large wheel, seen from above ; diameter from 0'14 mm. to 



0*2 mm. 

 ,,16. Deposits within the water- vascular system. 

 „ 17. Small wheel, seen from above ; diameter about 0'028 mm. 

 „ 18. Dichotomously branched body of about the same size as the small wheels. 

 „ 19. Spicula from the pedicels. 



