PLATE XVI 



Odinella nutrix 



Fig. I . Lateral aspect of base of ray of type at distal border of genital 

 inflation showing fifth and sixth skeletal arches with their sacculate 

 spines, x lo; ad, adambulacral spines;^,/), papulae. 



Fig. 2. Lateral aspect of ray, about midway between genital inflation and 

 tip, X 10 ; St. 42. On right the sacculi have been removed and skin 

 cleared to show plates and form of spines ; sacculus removed from 

 left inferomarginal spine ; midradial pad of pedicellariae on left without 

 a central spinelet. ad, adambulacral spines ; d, dorsolateral spines ; 

 i, inferomarginal spine, r, isolated midradial plate and spine; s, 

 superomarginal spine. 



Fig. 3. Lateral aspect of genital region of ray of male specimen, St. 42, 

 to show arrangement of skeletal arches, x 5 ; I-V, first 5 skeletal 

 arches, ad^, second adambulacral plate ; g, male gonopore ; the female 

 gonopore is in the position of "II"; i"^, second inferomarginal 

 (enlarged in fig. 5);/>, lower intercostal papulae. 



Fig. 4. Proximal end of same ray as fig. 3, showing narrow aperture to 

 disk and arrangement of plates, x 5. The aperture is partly occluded 

 by a dorsal diaphragm. 



Fig. 5. Enlargement ( x 20) of lower end of arch I of fig. 3, to show the 

 enlarged inferomarginal 2 (t^) with a lateral facet by which it is 

 joined to its fellow of the adjacent ray and to inferomarginal i (of 

 disk complex) by a small facet at i^. A similar non-muscular 

 symphysis at upper part of second adambulacral (ad^) joins it to its 

 fellow of adjacent ray ; a, ambulacral plate ; s, superomarginal. 



Fig. 6. Lateral aspect of tip of ray of the type, with sacculus removed, 

 showing the terminal spines of one side, x 20. 



Fig. 7. Lateral aspect of terminal plate of a specimen from St. 123, 

 X 20, showing the terminal organ in place but with rest of integu- 

 ment removed. 



Fig. 8. Ventral aspect of terminal complex of the largest specimen 

 (R 100 mm., St. 123), X 10. The compound terminal sacculus is 

 capable of much greater expansion. 



Fig. 9. Actinal surface of 2 rays of a young specimen in stage 2, from 

 brood pouch of type, x 30. 



Fig. 10. Actinal surface of one ray of a young specimen in stage 5, x 20. 



Fig. II. Abactinal view of a sector of a young specimen from brood 

 pouch of type, x 20. The dorsal wall is removed from 2 rays to 

 show the ambulacral plates. In the middle ray 3 plates of the first 

 skeletal arch have appeared, the middle one with pedicellariae; 

 ad, adambulacral spines; B, primary interradial plate; C, central 

 plate. 



