EXPLANATION OF PLATE XVIII. 



CLASS ECHINODERMS. 



Fig. 1. Sea-Slug or Sea-Cucumber, Cucitmaria frondota, a Holothurian 



eaten by the Chinese ; a, the branching tentacula which surround and 



fringe the mouth ; b, the five rows of perforations for the sucker-like 



feet ; c, the vent. 

 Fig. 2. Sea-egg or Sea-urchin; the vent at the apex. The mouth is beneath 



and central. The large tubercles in wide rows support the large spines ; 



the small perforations are for the passage of the sucker-like feet which 



assist in locomotion. 

 Fig. 3. Five-finger, radiated Star-fish, or Cross-fish, Anterias (Ur aster) san- 



guiiiolenta ; a, the eye spots at the extremity of each ray. 

 Fig. 4. Axterias ( If raster) rubcns ; a, both mouth and vent on the under side. 

 Fig. 5. Pentagonal Star-fish, Axterias tesselata. 

 Fig. 6. Medusa s-head, Gorgonocephalus, or Euryah, having five arms, 



which in some individuals branch off into 5,000 filaments. 

 Fig. 7. Pentacrinus Briareux, a, shows the head and arms; b, the upper 



part, half the natural size, with the arms entwined around the plated 



integument of the abdominal cavity, which terminates above by a sort 



of proboscis. 

 Fig. 8. Stone Lily, Lily Encrinite, Encrinus liliiformis. 



CLASS ACALEPH. 



Fig. 9. Rhizostoma Cuvieri ; a common jelly-fish of European seas; a, 



pedunculated mass depending from four roots in the center. 

 Fig. 10. Lymnorea triedra ; a, side view; b, view from above; c, eight 



finely divided appendages surrounding the long center proboscis. 

 Fig. 11. Rhodophysa helianthus ; a, the short bladder-like body ; b, rib-like 



gelatinous bodies, from which filamentous processes, c, depend. 

 Fig. 12. Callianira triploptera ; a, wing-shaped appendages fringed with 



a double row of vibrating cilia; b, a pair of long, branched, tentacu- 



lar-like appendages ; c, tubular body. 



CLASS PHYTOZOA, OR POLYPS. 



Fig. 13. Sea Anemone, Actinia. 



Fig. 14. Hydra fusca, a common fresh water polyp, highly magnified. 



Fig. 15. CaryophyUeO) Avith two series of numerous tentacula putting forth 

 from multiradiate cells. 



Fig. 16. Warty Gorgonia, or Warted Sea-Fan, Gorgonia verrucosa ; a, rep 

 resents the sucker-like feet ; b, the same magnified. 



Fig. 17. Sea-pen, Pennatula grisea. The branches put out on each side of 

 the central axis, like the barbs of a feather ; on these branches the 

 Polyps are situated, and by their tentacula its course seems to be di 

 rected. 



Fig. 18. Madrepora abratanoidcs ; a, twelve tentacles protruding from deep 

 cells. 



Fig. 19. Thick tentacled Fungia, swarming with numerous tentacula, all 

 belonging to one animal. 



Fig. 20. Fungia patellaris, Mushroom coral. 



CLASS PROTOZOA. 



Fig. 21. Rkizopods, Low forms allied to mollusks by their shells, as Fora- 



minifera, &c. 



Fig. 22. Polygastrica, (Animalcules, or microscopic animals.) 

 Fig. 23. Sponges Spongia ; a and b, sponges of commerce; c, tube sponge. 



