OPH IU RO ID EA .
gure 1. O ph io pl eu ra arctica, Duncan. The upper part o f th e disk and arms, natural
2 . The under surface o f th e disk, magnified.
2 a. The te e th on th e jaw-p late, oblique view, magnified.
2 b. The te e th , from above, magnified.
2 c. The te e th , approaching, magnified.
3. O p h io g l y p h a S a r s i i (Lutken). From-above, natural size.
4 . The underpart o f th e disk , magnified.
5 . O p h io g l y p h a r o b u s t a (Ayres). From above, natural size.
6 . The underpart o f th e disk and an arm, magnified.
7. The upper surface o f th e disk , magnified.
8. O p h io c t e n s e r ic e u m (Forbes). T h e upper surface, s lig h tly magnified.
9. The scaling o f th e upper part o f the disk and part o f an arm, magnified.
10. Part o f the underpart o f th e disk, magnified.
1 1 . O p h ia c a n t h a s p in u l o s a . The upper surface, natural size.
12. Part o f th e under surface, magnified.
13. The spines on th e disk, magnified.
14. O p h io c t e n s e r ic e u m (Forbes). P art o f th e d isk-scaling, magnified.
1 5 . A m p h iu r a H o lb c e l l i. Part o f th e underpart o f th e disk, magnified.
16. Radial shields, magnified.
17. Side view o f th e arm, magnified.