12 LYMAN ON NEW DEEP-SEA OPHIURANS. 



EXPLANATION OP PLATES. 

 Plate I. 



Fig. 1. OpMotholia suppUcans ; whole animal, seen from the side, with its arms raised vertically, 

 whereby the mouth-angles are turned down and outward, f 



Fig. 2. Ninth arm-joint, seen from the under side ; in the centre two large tentacles, each with its 

 long, spiniform scale ; on each side two regular arm-spines, and a cluster of the peculiar parasol-spines, or 

 pedicillariae. The central ridge is made by the junction of two side arm-plates, ^- 



Fig. 3. A parasol-spine stripped of its skin-bag and mounted on its little raamelon, -y- 



Fig. 4. Ophiohelus umhella ; upper side of disk with bases of two arms, showing how the parasol-spines 

 follow the normal ones ; also the arm-bones, divided in parallel halves, } 



Fig. 5. Lower side of disk, with mouth, Jj"- 



Fig. 6. A mouth-angle treated with potash, to show the underlying hard parts, On the sides are the 

 first two under arm-plates, and, in the centre, the closely soldered mouth-shield and side-shields, the sockets 

 of the second mouth-tentacles on either side, and the jaws, jaw-plate and tooth-papillae within. The little 

 circles indicate the bases of mouth-papillae, ^- 



Fig. 7. Two arm-joints, also treated with potash, to show the under and side arm-plates, two arm-spines 

 in position, and the articulation of the arm-bone above, -i^- 



Fig. 8. An arm-spine stripped of its skin, and showing the two parallel spicules that build it, ^- 



Fig. 9. Scales of disk, one of them bearing a minute spine, cleaned with potash to show their open 

 structure, and the mode of growth of the spine, ^- 



Fig. 10. A parasol-spine stripped of its skin-bag and mounted on a little mamelon. J-f-4 



Fig. 11. Ophiohelus pellucidus; lower side of disk with mouth, showing the tentacles. -ij"- 



Fig. 12. Upper side of disk, exhibiting the extremely delicate scales (to be seen only by a cross-light) 

 and the arm-bones divided in parallel halves, -ijfl- 



Fig. 13. 9th, 10th and 11th arm-joints stripped of skin. On the 9th are three normal spines and one 

 parasol-spine ; on the 10th and 11th, only two rows of the latter form, Y- 



Fig. 14. A parasol-spine stripped of skin and mounted on its little mamelon, -^ 



Fig. 15. A normal spine, treated with potash, and showing that it is composed of two spicules like that 

 of 0. umhella, Sf- 



Fig. 16. Ophiohelus umhella; a joint close to tip of arm, digested with potash; seen from above. On 

 the upper side is the film-like upper arm-plate pierced with numerous holes ; to the right and left of it is a 

 side arm-plate, also of open structure and having a spine-ridge which consists of two or three crowded, 

 irregular rows of elongated mamelons. On the right, these niamelons are shown carrying their parasol- 

 spines. Underneath are the curious, curved, translucent bars that are the two halves of the arm-bone, uni- 

 ted only at their articulating ends. Y" 



Plate II. 



I'ig. 17. Ophioehytra epigrus, from below, | 



Fig. 18. " " from above, | 



Fig. 19. " " arm-joints in profile, | 



Fig. 20. Ophiacantha placentigera, from below, f 



Fig. 21. " " from above, f 



Fig. 22. " " arm-joints in profile, J 



Fig. 23. Ophiopeza aqualis, from below, | 



Fio-. 24. '' " from above, | 



Fig. 25. " " arm-joints in profile, f 



Fig. 26. Ophiactis pectorale, from below, | 



Fig. 27. " " from above, | 



Fiff. 28. " " arm-joints in profile, | 



Fig. 29. OpMambix aculeatus, from below, f 



Fig. 80. " " fi'om above, \- 



Fig. 31. " " arm-joints in profile, f 



