PLATE VIII 



ONTOGENY OF OERITHIID^ (COIltiUUed) 



Fig. 1. Ccrithiiini citllisoiiiu. sixth volutiou. 1.8 X. 8 mm. 



Fig. 2. Cerithimn callisonia. eighth volutiou. 2.G X 1 mm. 



Fig. 3. Cerithimn vtctikci, fifth volution. 1.8 X 1 mm. 



Fig. 4. Viciiioccrithiiim paraUclitni. fifth volution. 2.4 X 1 mm. 



Fig. 5. Vicinocerithiinn parallcluni, seventh volutiou. 3 X 2 mm. 



Fig. 6. Vicinoceriihimn bouei, eighth volutiou. 2.8, X 1.4mm. 



Fig. 7. Polamidopsis tricarinata, sixth volution. 1.4 X .6 mm. 



Fig. 8. I'otuiiiidoi)sis tricarinata, tenth volution. 2.7 X 1mm. 



B"'iG. 9. Potaniidopsis trochlcarc, sixth volution. 1.3 X .5 mm. 



Fig. 10. Potatnidopsis trochleare, twelfth volution. 11.8 X 7.5mm. 



