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



PLATE XVI. 



Asthenosoma grubii, A. Ag. (figs. 1-13), p. 82. 



Y'lSf. 1 . Seen from the actinal side ; natural size. 



2. Short spine with membraneous sheath from the abactinal surface of fig. 1, Plate 

 XV., enlarged. 



3, 4. Longer spines with membraneous sheaths. 

 5. Short, sharp miliary spine. 

 6 a, b, c. Different parts of spine (fig. 4) without membraneous sheath. 



7. Short spine with club-shaped membraneous sheath at tip. 



8. Another spine of same kind as fig. 7. 



9. Same spine, different view. 



10. Large short-stemmed pedicellaria of actinal surface. 



11. Small-headed, long-stemmed pedicellaria of the abactinal surface. 



1 2. Long-stemmed trifid pedicellaria of the actinal surface. 



13. Somewhat smaller pedicellaria of same kind as fig. 12, expanded. 



. PLATE XVIL 



Asthenosoma grubii, A. Ag. (figs. 1-6), p. 82. 

 Segment of test seen from the actinal side, denuded of spines ; natural size. 

 Denuded segment of the test, abactinal side, natural size. 

 Magnified view of abactinal system. 

 Magnified view of actinal system. 

 Portion of the ambulacral system, abactinal side. 



Portion of the ambulacral system, actinal side. The tubercles on figs. 1 and 2 

 are for the greater part pei'forated. 



PLATE XVIP. 



Asthenosoma gracile, A. Ag. (figs. 1-4), p. 89. 



Fig. 1. Seen from the abactinal surface ; natural size. 



2. Abactinal system denuded (f ). 



3. Coronal plates of actinal surface near the ambitus (f ). 



4. Coronal plates of the abactinal surface near the ambitus (f). 



Asthenosoma coriaceum, A. Ag. (figs. 5-7), p. 88. 



5. Denuded abactinal system of specimen measuring 212 mm. in diameter; natural 



size. 



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