The Voyage of H.M.S.„Challenger." 



Hexactinellida Pl.XCHI. 



6. 



PE SchiJze and 5Pij-t5c}i del. 



L-.lK AistvWeintr k Wintec FranMurl'/M 



TRETODICTYUM TUBULOSUM. F ESchulze. 



