104 



Fig. 16. One of the exterior furrow- spines with its cuticular sheath. 

 Fig. 17. The point of the calcareous spine itself, strongly magnified. 

 Fig. 18, 10. Interior furrow-spines. 

 Fig. 20, 21. 2 of the furrow-spines of the disc. 



Fig. 22. A water-foot magnified, shewing the numerous muscular fibres crossing 

 each other. 



Tab. II. 



Fig. 1. A full grown 10-armed specimen of Br. coronata, viewed from above, natural 

 size; only one of the arms drawn. 



Fig. 2. An other specimen with 12 arms, of which 2 are drawn; one recently 

 regenerated and still without evident calcareous ribs. 



Fig. 3. The extremity of a monstrously developed bifurcated arm, viewed from 

 above, natural size. 



Fig. 4. The basal part of an arm, with strongly projecting calcareous ribs, aud 

 unusually numerous and interrupted bands of pedicellaries, natural size. 



Fig. 5. The extremity of an arm viewed from the side, strongly magnified, shewing 

 the dorsal bands of pedicellaries (a) the terminal organ of sense (c) and the peculiar plate 

 (b) which shelters it. 



Fig. 6. The same seen from below: b, c, as in the preceding figure. 



Fig. 7. The terminal organ of sense, still more strongly magnified, seen from the 

 side: b, the 2 exterior rudimentary water- feet. 



Fig. S. The disc of a full grown 11-armed specimen seen from above, slightly 

 magnified. The dorsal skin is cut open round the periphery and turned back, in order to 

 shew the subjacent interior organs: a, the madreporic body; b, the dorsal skin turned back; 

 c c, the basal trunks of the radial caeca (to the right a bifurcation of one these indicated); 

 d, the peripheral part of the stomach; e, the upper vault of the stomach, with its radial 

 folds; /; the apparatus of secretion; g, section of excretory duct for the same; h, the 

 porus secretorius which perforates the dorsal skin. 



Fig. .9. A piece of the peripheral part of the stomach viewed from within, shewing 

 the numerous sinuous longitudinal folds: a, tendinous fibres whereby this part is attached to 

 the oral ring; b, the oral membrane. 



Fig. 10. The upper vault of the stomach viewed from the under or interior side, 

 shewing the numerous papillae issuing from the same, and the terminal trunks of the radial 

 caeca preceding from the periphery. 



