PLATE Xn. 



Hippasteria imperialis. 



178. Abactiual view, x 0.5. 



179. Aetinal view, x 0.5. 



180. Abactinal view of a small specimen, x 1. 



181. Aetinal view of same, x 1. 



182. Mouth-plates, x 2. 



183. Ninth ndambulacral plate. The upper side is the adcentral 



end. X G. 



184. INIargiuals. Tlie upper roAv is the superomarginal, the cleft at 



the middle the interradial line. X 2. 



185. Ventrolateral plate somewhat near the lx)rder of disk and the 



ambulacral fm'row. x 4.5. 



186. Ventrolateral, x 4.5. 



187. Abactinal i^thiU). x 5. 



188. Ditto, x 5. 



189. Ditto. X 5. 



190. Valves of an adambulacral pediceUaria. x 50. 



191. Valve of a ventrolateral pedicellaria. x 50. 



192. Valve of an abactinal pedicellaria. x 50. 



193. Madreporite. The right side is the outer, x 7. 



