Plate XIX. 

 The Calycinal System of Brissopsis; young of Echinus. 



Till' ralv.v (il a spc'ciinuii ol Urissopsis Iviilciii I-Okk., of 9 ; 7 iniii. 



The same, at 11:9 mm. 



The same, at 1.5 : 12 mm. 



The same, at IT) ; 13 mm, 



'I"he same, at Ifi : K5 nun 



The same, at 38 : .3.5 mm., having a number of madreporic pores in tije iiiteiradiuin ."i. 



The same, at 42 , 38; the eostal 2 without sexiial pore. 



The same, at 44:40; the madreporitc spreading- ontside the sexual pore in the costal 1. 



The same in a nearly full-!;rown specimen, with a larijer numlicr of madieporic pore? in the interra- 

 dium 5. and a few in the amljulacrnm I. 

 Fiij. 232, Echinus S]). younsr, (j,fi mm., astomous. aproctic. jejune, same specimen as thai descg-ilicd m Ktudcs 



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

 Fia'. 233. Tlie same, ventral view. 



