Plate IV. 



Fig. i. Apical area of Phormosoma placenta, diameter 37 mm . +/i- 



— mm 8/ 



— 2. - - — — 7 • /i- 



— 3- Sperosoma Grimaldii, abactinal side. 



_ 4—^. — — young specimen; 4. abactinal side, 5. actinal side. 



