Platk XIX. 



The Calycinal System of Bris»opsis; young of Echinus. 



P. 75. 



Fig. 223. The ealyx of a specimen of Brissopsis lyrifera FoRB., of 9 : 7 mm. 



Fig. 224. The same, at 11:9 mm. 



Fig. 225. The same, at 1.5 : 12 ram. 



Fig. 226. The same, at 15 : 13 mm. 



Fig. 227. The same, at 16 : 13 mm. 



Fig. 228. The same, at 38 : 35 mm., having a nuraber of madreporic pores in the iiiterradium 5. 



Fig. 229. The same, at 42 : 38; the costal 2 without sexual pore. 



Fig. 230. The same, at 44 : 40; the madreporite spreading outside tlie sexual pore in the costal 1. 



Fig. 231. The same in a nearly full-grown specimen, with a larger number of madreporic pores in the interra- 



dium 5, and a few in the ambulacrura I. 



Fig. 232. Echinus sp. voung, 0,6 mm., astoraous, aproctic, jejune, same specimen as that desca'ibed in Etudes 



p. 27, pl.'XVli, fig. 149—152; dorsal view; p. 25. 



Fig. 233. The same, ventral view. 



