Plate IV. 



Fig. I. Apical area of Pliorinosonia placenta, diameter 37™". 4/^. 



o _ '7min 8/ 



— 3. Sperosoma Gi'niiaid/'i\ abactinal side. 



— 4 — 5. — — young speciraeu; 4. abactinal side, 5. actinal side. 



