109 



Tab. V. 



Fig. 1. skeleton of the disc (the oral ring), with the base of the skeleton of 3 

 arms in their natural connexion, of a 9-armed specimen of Brisinga coronata, viewed 

 from above. 



Fig. 2. The same viewed from bolow. 



Fig. 3. A complete arm-vertebra seen from above. 



Fig. 4. The same viewed from the left side. 



Fig. 5. The same viewed from the aboral extremity. 



Fig. 6. The same viewed from below. 



The following indication will serve for the 4 last figures: 

 a, interior part of the ambulacral plates. 

 &, lateral parts of the ambulacral plates. 

 ad, the adambulacral plates. 



Fig. 7. The part of the skeleton of a 9-armed specimen of Solaster endeca 

 corresponding to fig. 1, viewed from above. 



Fig. 8. A part of the same viewed from below, for comparison with fig. 2. 

 Fig. 9. An interradium with 2 half radii of the skeleton of Brisinga coronata repre- 

 sented in fig. 1. 



Fig. 10. The corresponding part of the skeleton of the Solaster endeca represented 

 in fig. 7. 



In both figures the letters indicate corresponding parts: 

 1, 2, 3, 4, 5 ambulacral plates in their order: 

 ad, adambulacral plates. 

 r, dorsal marginal plates. 

 p p, parietal plates. 

 w, wedge-plates. 



o, aperture for the passage of the radial ambulacral vessel. 



x, the border of the oral ring, which below limits the furrow for the circular ambu- 

 lacral vessel. 

 I, ligaments. 



Fig. 11. A part of the skeleton of the disc (the oral ring) with the base of 3 arms 

 of the young Br. coronata represented in Tab. IV, fig. 38-40, viewed from above, strongly 

 magnified: ad, the adambulacral plates of the disc; r, rudimentary dorsal marginal plates; 

 iv, wedge-plate. 



Fig. 12. The same viewed from below: ad 2 , the second pair of adambulacral 

 plates (here evidently belonging to the arms); s, embryonic furrow-spines; x, the circular 

 rim which proceeds from the interior wall of the oral ring, and to which the oral membrane 

 is attached. 



