PLATE IV. 



Page 

 Fig. 1. STRUCTURE OF OPHTURUS. , h, c. PLUTEUS 



PARADOXUS 194 



Pig. 2. OPHIOCOMA 199 



Fig. 3. ASTERIAS. a, b, c, d, e,f, g. Phases of develop- 

 ment of young 201 



Fig. 4. SOLEASTER, or TWELVE-RAYED STAR-FISH. 



Fig. 5. SPATAISTGUS PURPUREUS 214 



Fig. 6. ECHINUS ESCULENTUS. b. Pedicellaria. 



c, d. Structure of mouth of Echinus 215 



Fig. 7. HOLOTHURIA. a, b. Larva condition 237 



Fig. 8. HOLOTHURIA CECNUS. b, c. The animal in pro- 

 cess of spontaneous division 246 



