PLATE I.
H OLOTHUROIDEA.
jure 1. C u c u m a r ia fr o n d o sa (Gunn.), Forbes. N a tu ra l size'.
2. A y o u n g specimen^ o f th e same, natural size.
3 . Cucumaria calcigera (Stim p .), Selenka. N a tu ra l size.
4 . Sk etch o f th e mou th -rin g and adjacent parts o f a y o u n g individual, magnified.
5 . Generative tubes at an early sta g e o f growth, magnified.
6 . Spicules o f th e superficial layer in s itu , magnified.
• 7. Sm all spicule in profile, magnified.
8 . D isk at th e ex trem ity o f the- sucker-foot, magnified.
9. P so lu s F a b r ic i i (D . & K .), L iitk en . Dorsal aspect, natural size.
10. T h e same specimen. Ven tra l aspect, natural size.
1 1 . A y ou n g specimen. Ven tral aspect, natural size.
1 2 . On6 o f th e small cup-like spicules o f th e ventral in teg um en t, magnified. _
1 3 . Spicules o f th e ventral in tegum en t, magnified.
14. C h ir o d o t a LjEv is (Fabr.), Grube. N a tu ra l size.
15. Generative tubes* magnified.
16. P ortion o f th e mouth-ring, magnified.
17. The pyriform infundibular organs or “ Wimpertrichter,” magnified.
18. One o f th e w h eel-lik e spicules, magnified.
19. One o f th e sacculi, to show th e aggregation o f th e spicules, magnified.
2 0 . M y r io t r o c h u s R i n k i i , Steenstrup. N atu ral size.
2 1 . One o f th e spicules, magnified.
2 2 . Sketch o f th e internal organs, showing th e relative proportions o f the alimentary canal,
th e Po lian vesicle, and th e generative tubes.
2 3 . P ortion o f th e mouth-ring, magnified. (In th is drawing th e upward p rolongations ought
to taper more rapidly, and th e foramina o u gh t to b e further up from th e base.)
24. Underside o f th e mouth-ring, w ith parts attached, seen from below, showing th e dilatations
o f th e oral water-vessel.
Arctic/ Holotfvuroidew.