Plate IV. 



Fig. I. Apical area of Phormosoiiia placenta^ diameter 37'nm y^ 



— 2. — - - — — — 7"™- 7i- 



— 3. Sperosoma Grimaldu, abactinal side. 



— 4—5. — — j-ouug specimen; 4. abactinal side, 5. actinal side. 



