AND PELAGIC SURFACE-SWIMMING SPECIES. 305 



Fig. 10. The same, seen in vertical section, to show the form of the oral disk, the mode of origin of the 

 tentacles, and peculiar cavity in the base. Figs. 9 and 10 both half natural size. 



Fig. 11. Edwardsia coriacea, at rest, with the tentacles expanded. Twice the natural size. 



Fig. 12. The same, when completely contracted. 



Fig. 13. Portion of the disk, with three tentacles enlarged, to show the colouring. 



Fig. 14. Arrangement of the coloured streaks on the body-wall of the same, immediately beneath the 

 edge of the disk. 



Fig. 15. Cerianthus bathymetricus. Tube of the animal viewed intact, of natural size. 



Fig. 16. The same, tube laid open, to show the animal in situ. 



Fig. 17. The same, animal laid open and dissected. T, Outer tentacles ; t, inner tentacles; or, mouth 

 and plaited upper region of the digestive tube; s, stomach, or lower portion of the digestive 

 tube, in which were found the remains of a crustacean ; m, mesenteries, from which proceed in 

 one region three muscular threads, which are prolonged to the apex of the body near the 

 posterior opening, where they are attached ; g, generative glands. 



Fig. 18. Large nematocyst of same, and of the kind of which the tube or test is mainly composed. 



Fig. 19. Second form of nematocyst of same. 



Fig. 20. Small Nematoid parasite occurring in the wall of the tube. 



