Plate XVIII. 



The Calycinal System of Spatangidae. 



p. 74. 



Fig. -'09. Till! ciilyx of a s[)(:ciiiiuii of f>pat;iii!jiis piirpuvcus O. F. M., of 5:4 mm. 



F^ig. 210. The same, at 13,5 : 12 mm. 



Fig. 211. The same, at 14:13 ram. 



F'ig. 212. The same, at 15 : 14 ram. 



Fig. 213. The same, at 16: 14 mm. 



Fig. 214. The same, at 16 ; 15 mm. 



Fig. 215. The same, at 18; 16 mm. 



Fig. 216. The same, at 19 : 18 mm. 



Fig. 217. The same, at 24 : 21 mm. 



Fig. 218. The same, at 23:22 mm. 



Fig. 211). The same, at 53:50 mm. .\ single uia(lri:poi-ic pore, markttl *, outside the calyx. 



Fig. 220. The calyx of Abatus eavcriiosus Phil. 



Fig. 221. The same of Hemiastcr bufo .\l. Brogn. 



Fig. 222. The same of Hemiastcr expergitus Lov. 



