PLATE IV V 



ONTOGENY OF SIX SPECIKS OF CERITHIUM (COIltiUUed) 



Fig. 1. Ccrithium tuberosum, eighth volution. 4.6 X 2.2 rum. 



Fig. 2. Ccrithium adansoni, fifth volutiou. 3.5 X 1.5 mm. 



Fig. 3. Cerithiuvi adansoni, eighth volution. 9 X 3.4 mm. -^^ 



Fig. 4. Cerithium? iiodulosuni, sixth volution. 6 X 3 mm. 



Fig. 5. Cerithium? nodulosum, eighth volution. G X 5 mm. Later whorls of 



this shell are not figured, as they are too large to show details when 



reduced to the scale of this plate. 

 Fig. 0. Pseudovcrtainis aluco, seventh volution. 5.2 X 2.3 mm. 

 Fig. 7. Pseudorertayus aluco, eighth volution. 7 X 3 mm. 

 Fig. 8. Cerithium lamcUosum, fifth volution. 1.2 X .5 mm. 

 Fig. 9. Cerithium retardatum, fifth volution. 1.2 x .5 mm. 

 Fig. 10. Cerithium, retardatum, seventh volutiou. 2X1 nun. 



