Plate XVIII. 



The Calycinal System of Spatangidae. 



P. 74, 



Fig. 209. The calyx of a specinien of Spataiitrus puvpureus O. F. M., of 5:4 ram. 



Fig. 210. The same, at 13,5 : 12 mm. 



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



Fig. 212. The same, at 15 : 14 mm. 



Fig-. 213. The same, at 15 : 14 ram. 



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



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



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



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



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



Fig. 219. The same, at 53:50 mm. A sitigie madveporic pore, marked*, outsidc the calyx. 



Fig. 220. The calyx of Abatus caveniosus Phil. 



Fig. 221. The same of Hemiaster buio Al. Brogn. 



F^ig. 222. The same of Hemiaster expergitus Lov. 



