PLATE VI 



ONTOGENY OF SIX SPECIES OF cERiTHiuM (Continued) 



Fig. 1. CcrlthiKin tHhcrosion. thirteenth volution. 12 X 11.5 mm. 

 Fig. 2. Vcrithium tuhcrosiiiii, fourteenth volution. 24x29 mm. 

 Fig. 3. Cerithiuin wquitiijirale, fourteenth volution. 9.5x9.2 mm. 

 Fig. 4. Pseudovertagus aluco, thirteenth volution. 19 X 11 mm. 

 Fig. 5. Pseudovertagus aluco, fourteenth volution. 22 X 20 mm. 

 Fig. 6. Cerithiuin lauicllosunt, aperture. 12 X 11 mm. 

 Fig. 7. Cerithium retardatuiii. fourteenth volution. 8.5 X 4 mm. 

 Fig. 8. Cerithium retardatuin, aperture. Tx9mm. 



